Harold Erickson

Overview:

Cytoskeleton: It is now clear that the actin and microtubule cytoskeleton originated in bacteria. Our major research is on FtsZ, the bacterial tubulin homolog, which assembles into a contractile ring that divides the bacterium. We have studied FtsZ assembly in vitro, and found that it assembles into thin protofilaments (pfs). Dozens of these pfs are further clustered to form the contractile Z-ring in vivo. Some important discoveries in the last ten years include:

•    Reconstitution of Z rings in vitro. We provided FtsZ with a membrane tether, and found that when incorporated inside liposomes, FtsZ-mts can assemble Z rings without any other proteins.

•    These reconstituted Z rings generate a constriction force on the membranes, again without any other proteins (no motor molecules).

•    The constriction force is generated by a curved conformation of FtsZ pfs generating a bending force on the membrane.

Important questions for the future are:

  • How are FtsZ pfs arranged in the Z ring? We favor the ribbon model, where pfs are parallel and laterally associated into a ribbon. Many others in the field favor a scattered model, where pfs are more widely separated. We are exploring new electron microscopy (EM) methods to resolve the structure. We have also developed new tools to facilitate superresolution light microscopy (PALM).
  • How does FtsZ treadmilling work? Our lab provided the first evidence that FtsZ treadmills, adding subunits at one end and losing them at the other (Redick J Bact 2005). This has now been confirmed in vitro and in vivo. We are developing theoretical models and experimental (EM) methods to determine the detailed mechanism of treadmilling.
  • What is the structure of the septum in dividing bacteria? There is wide agreement that Gram-positive bacteria divide by ingression of a plate-like septum. Conventional EM suggests that Gram-negative bacteria have a shallower V-shaped constriction. We are revisiting this using novel fixatives and high-pressure freezing for thin section EM.
Irisin. We believe the irisin story is bunk. Irisin was proposed in 2012 as a novel myokine, secreted by muscle cells in response to exercise, it induces the transformation of white fat to brown fat. This inspired hopes of an exercise pill that might correct obesity and other metabolic disorders. We have argued that the original discovery was flawed in several respects (Erickson, Adipocyte, 2013), and that the 300+ published follow-up studies are based on flawed commercial antibodies (Albrecht et al, Sci Rep 2015). We are now developing new assays to determine if irisin exists in in the blood of humans, primates and other animals. We expect it does not, especially in humans whose FNDC5 gene has a mutated start codon.

Positions:

James B. Duke Distinguished Professor of Cell Biology

Cell Biology
School of Medicine

Professor of Cell Biology

Cell Biology
School of Medicine

Professor of Biomedical Engineering

Biomedical Engineering
Pratt School of Engineering

Professor of Biochemistry

Biochemistry
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 1968

Johns Hopkins University

Grants:

Zeiss LSM510 META confocal-fluorescence spectroscopy

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Structure and Assembly Dynamics of FtsZ

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Extracellular Matrix and Cell Attachment Proteins

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Assembly, Dynamics and Regulation of Chloroplast FtsZ

Administered By
Cell Biology
Awarded By
Michigan State University
Role
Principal Investigator
Start Date
End Date

A Genomic and Structural Study of FTsZ Constriction in Cell Divison

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Publications:

L form bacteria growth in low-osmolality medium.

L form bacteria do not have a cell wall and are thought to require medium of high osmolality for survival and growth. In this study we tested whether L forms can adapt to growth in lower osmolality medium. We first tested the Escherichia coli L form NC-7, generated in 1987 by Onoda following heavy mutagenesis. We started with growth in osmoprotective medium (~ 764 mOsm kg-1) and diluted it stepwise into medium of lower osmolality. At each step the cells were given up to 10 days to adapt and begin growing, during which they apparently acquired multiple new mutations. We eventually obtained a strain that could grow in LB containing only 34 mM NaCl, 137 mOsm kg-1 total. NC-7 showed a variety of morphologies including spherical, angular and cylindrical cells. Some cells extruded a bud that appeared to be the outer membrane enclosing an enlarged periplasm. Additional evidence for an outer membrane was sensitivity of the cells to the compound CHIR-090, which blocks the LPS pathway, and to EDTA which chelates Mg that may stabilize and rigidify the LPS in the outer membrane. We suggest that the mechanical rigidity of the outer membrane enables the angular shapes and provides some resistance to turgor in the low-osmolality media. Interestingly, cells that had an elongated shape underwent division shortly after addition of EDTA, suggesting that reducing the rigidity of the outer membrane under some turgor pressure induces division before lysis occurs. We then tested a well-characterized L form from Bacillus subtilis. L form strain LR-2L grew well with sucrose at 1246 and 791 mOsm kg-1. It survived when diluted directly into 440 mOsm kg-1 but grew poorly, achieving only 1/10 to 1/5 the density. The B. subtilis L form apparently adapted to this direct dilution by rapidly reducing cytoplasmic osmolality.
Authors
Osawa, M; Erickson, HP
MLA Citation
Osawa, Masaki, and Harold P. Erickson. “L form bacteria growth in low-osmolality medium..” Microbiology, vol. 165, no. 8, Aug. 2019, pp. 842–51. Pubmed, doi:10.1099/mic.0.000799.
URI
https://scholars.duke.edu/individual/pub1379658
PMID
30958258
Source
pubmed
Published In
Microbiology
Volume
165
Published Date
Start Page
842
End Page
851
DOI
10.1099/mic.0.000799

The discovery of the prokaryotic cytoskeleton: 25th anniversary.

The year 2017 marks the 25th anniversary of the discovery of homologues of tubulin and actin in prokaryotes. Before 1992, it was largely accepted that tubulin and actin were unique to eukaryotes. Then three laboratories independently discovered that FtsZ, a protein already known as a key player in bacterial cytokinesis, had the "tubulin signature sequence" present in all α-, β-, and γ-tubulins. That same year, three candidates for bacterial actins were discovered in silico. X-ray crystal structures have since confirmed multiple bacterial proteins to be homologues of eukaryotic tubulin and actin. Tubulin and actin were apparently derived from bacterial precursors that had already evolved a wide range of cytoskeletal functions.
Authors
MLA Citation
Erickson, Harold P. “The discovery of the prokaryotic cytoskeleton: 25th anniversary..” Mol Biol Cell, vol. 28, no. 3, Feb. 2017, pp. 357–58. Pubmed, doi:10.1091/mbc.E16-03-0183.
URI
https://scholars.duke.edu/individual/pub1227942
PMID
28137947
Source
pubmed
Published In
Molecular Biology of the Cell
Volume
28
Published Date
Start Page
357
End Page
358
DOI
10.1091/mbc.E16-03-0183

Rapid in vitro assembly of Caulobacter crescentus FtsZ protein at pH 6.5 and 7.2.

FtsZ from most bacteria assembles rapidly in vitro, reaching a steady-state plateau in 5-10 s after addition of GTP. A recent study used a novel dynamic light-scattering technique to assay the assembly of FtsZ from Caulobacter crescentus (CcFtsZ) and reported that assembly required 10 min, ∼100 times slower than for related bacteria. Previous studies had indicated normal, rapid assembly of CcFtsZ. We have reinvestigated the assembly kinetics using a mutant L72W, where assembly of subunits into protofilaments results in a significant increase in tryptophan fluorescence. We found that assembly reached a plateau in 5-10 s and showed no change in the following 10 min. This was confirmed by 90° light scattering and negative-stain electron microscopy. The very slow kinetics in the dynamic light-scattering study may be related to a refractory state induced when the FtsZ protein is stored without nucleotide, a phenomenon that we had observed in a previous study of EcFtsZ. We conclude that CcFtsZ is not an outlier, but shows rapid assembly kinetics similar to FtsZ from related bacteria.
Authors
Milam, SL; Erickson, HP
MLA Citation
Milam, Sara L., and Harold P. Erickson. “Rapid in vitro assembly of Caulobacter crescentus FtsZ protein at pH 6.5 and 7.2..” J Biol Chem, vol. 288, no. 33, Aug. 2013, pp. 23675–79. Pubmed, doi:10.1074/jbc.M113.491845.
URI
https://scholars.duke.edu/individual/pub954385
PMID
23824192
Source
pubmed
Published In
The Journal of Biological Chemistry
Volume
288
Published Date
Start Page
23675
End Page
23679
DOI
10.1074/jbc.M113.491845

BtubA-BtubB heterodimer is an essential intermediate in protofilament assembly.

BACKGROUND: BtubA and BtubB are two tubulin-like genes found in the bacterium Prosthecobacter. Our work and a previous crystal structure suggest that BtubB corresponds to alpha-tubulin and BtubA to beta-tubulin. A 1:1 mixture of the two proteins assembles into tubulin-like protofilaments, which further aggregate into pairs and bundles. The proteins also form a BtubA/B heterodimer, which appears to be a repeating subunit in the protofilament. METHODOLOGY/PRINCIPAL FINDINGS: We have designed point mutations to disrupt the longitudinal interfaces bonding subunits into protofilaments. The mutants are in two classes, within dimers and between dimers. We have characterized one mutant of each class for BtubA and BtubB. When mixed 1:1 with a wild type partner, none of the mutants were capable of assembly. An excess of between-dimer mutants could depolymerize preformed wild type polymers, while within-dimer mutants had no activity. CONCLUSIONS: An essential first step in assembly of BtubA + BtubB is formation of a heterodimer. An excess of between-dimer mutants depolymerize wild type BtubA/B by sequestering the partner wild type subunit into inactive dimers. Within-dimer mutants cannot form dimers and have no activity.
Authors
Sontag, CA; Sage, H; Erickson, HP
MLA Citation
Sontag, Christopher A., et al. “BtubA-BtubB heterodimer is an essential intermediate in protofilament assembly..” Plos One, vol. 4, no. 9, Sept. 2009. Pubmed, doi:10.1371/journal.pone.0007253.
URI
https://scholars.duke.edu/individual/pub731120
PMID
19787042
Source
pubmed
Published In
Plos One
Volume
4
Published Date
Start Page
e7253
DOI
10.1371/journal.pone.0007253

The RGD motif in fibronectin is essential for development but dispensable for fibril assembly.

Fibronectin (FN) is secreted as a disulfide-bonded FN dimer. Each subunit contains three types of repeating modules: FN-I, FN-II, and FN-III. The interactions of alpha5beta1 or alphav integrins with the RGD motif of FN-III repeat 10 (FN-III10) are considered an essential step in the assembly of FN fibrils. To test this hypothesis in vivo, we replaced the RGD motif with the inactive RGE in mice. FN-RGE homozygous embryos die at embryonic day 10 with shortened posterior trunk, absent tail bud-derived somites, and severe vascular defects resembling the phenotype of alpha5 integrin-deficient mice. Surprisingly, the absence of a functional RGD motif in FN did not compromise assembly of an FN matrix in mutant embryos or on mutant cells. Matrix assembly assays and solid-phase binding assays reveal that alphavbeta3 integrin assembles FN-RGE by binding an isoDGR motif in FN-I5, which is generated by the nonenzymatic rearrangement of asparagines (N) into an iso-aspartate (iso-D). Our findings demonstrate that FN contains a novel motif for integrin binding and fibril formation whose activity is controlled by amino acid modification.
Authors
Takahashi, S; Leiss, M; Moser, M; Ohashi, T; Kitao, T; Heckmann, D; Pfeifer, A; Kessler, H; Takagi, J; Erickson, HP; Fässler, R
MLA Citation
Takahashi, Seiichiro, et al. “The RGD motif in fibronectin is essential for development but dispensable for fibril assembly..” J Cell Biol, vol. 178, no. 1, July 2007, pp. 167–78. Pubmed, doi:10.1083/jcb.200703021.
URI
https://scholars.duke.edu/individual/pub706568
PMID
17591922
Source
pubmed
Published In
The Journal of Cell Biology
Volume
178
Published Date
Start Page
167
End Page
178
DOI
10.1083/jcb.200703021

Research Areas:

Acquired Immunodeficiency Syndrome
Acrylamide
Actin Cytoskeleton
Actins
Adenosine Triphosphatases
Adenosine Triphosphate
Age Factors
Alkaline Phosphatase
Allosteric Regulation
Alternative Splicing
Amidohydrolases
Amino Acid Motifs
Amino Acid Sequence
Amino Acid Substitution
Anion Exchange Resins
Annexin A2
Antibodies
Antibodies, Monoclonal
Antigens, CD
Antigens, CD18
Antigens, CD29
Antigens, Differentiation
Antigens, Nuclear
Antigens, Surface
Aorta
Archaea
Archaeal Proteins
Artificial Gene Fusion
Aspartic Acid
Astrocytes
Astrocytoma
Azotobacter vinelandii
Bacillus anthracis
Bacillus subtilis
Bacillus thuringiensis
Bacteria
Bacterial Physiological Phenomena
Bacterial Proteins
Base Sequence
Binding Sites
Binding Sites, Antibody
Binding, Competitive
Biochemistry
Biological Evolution
Biophysical Phenomena
Biophysics
Biopolymers
Blood Coagulation Factors
Blood Platelets
Blotting, Northern
Blotting, Western
Bone Marrow
Bone Neoplasms
Brain
Brain Chemistry
Brain Injuries
Buffers
CD18 Antigens
CHO Cells
Caenorhabditis elegans Proteins
Calcium
Calmodulin-Binding Proteins
Calorimetry
Carrier Proteins
Catalytic Domain
Cations
Cations, Divalent
Cattle
Caulobacter crescentus
Cell Adhesion
Cell Adhesion Molecules
Cell Adhesion Molecules, Neuronal
Cell Cycle Proteins
Cell Differentiation
Cell Division
Cell Line
Cell Line, Transformed
Cell Membrane
Cell Movement
Cell Separation
Cell Survival
Cell Transformation, Neoplastic
Cells, Cultured
Central Nervous System
Centrifugation
Centrifugation, Density Gradient
Cereals
Chelating Agents
Chemical Fractionation
Chemical Phenomena
Chemical Precipitation
Chemistry
Chemistry, Physical
Chemokine CX3CL1
Chemokines, CX3C
Chemokines, CXC
Chick Embryo
Chickens
Child
Chimera
Chondrocytes
Chondroitin Sulfate Proteoglycans
Chondroitin Sulfates
Chromaffin System
Chromatography
Chromatography, Affinity
Chromatography, High Pressure Liquid
Chromatography, Ion Exchange
Chromatography, Liquid
Chromosomal Proteins, Non-Histone
Chromosome Deletion
Chromosome Segregation
Chromosomes
Chromosomes, Bacterial
Cloning, Molecular
Colchicine
Cold Temperature
Collagen
Computer Simulation
Connective Tissue Diseases
Cricetinae
Cross-Linking Reagents
Crystallization
Crystallography
Crystallography, X-Ray
Culture Media
Culture Media, Conditioned
Culture Techniques
Cycloheximide
Cysteine
Cytokines
Cytokinesis
Cytoplasm
Cytoskeletal Proteins
Cytoskeleton
DEAE-Dextran
DNA
DNA Helicases
DNA Ligases
DNA Repair
DNA Replication
DNA, Bacterial
DNA, Circular
DNA, Complementary
DNA-Binding Proteins
Dactinomycin
Detergents
Dextrans
Diffusion
Dimerization
Disulfides
Dithiothreitol
Dogs
Dose-Response Relationship, Drug
Down-Regulation
Drosophila
Drosophila Proteins
Drosophila melanogaster
Drug Interactions
Drug Stability
E-Selectin
Edetic Acid
Edible Grain
Elasticity
Electrophoresis, Gel, Two-Dimensional
Electrophoresis, Polyacrylamide Gel
Embryo Implantation
Embryo, Mammalian
Embryonic and Fetal Development
Endopeptidases
Endosomal Sorting Complexes Required for Transport
Endothelial Cells
Endothelium
Endothelium, Vascular
Energy Metabolism
Entropy
Enzyme Activation
Epidermal Growth Factor
Epidermis
Epithelium
Epitope Mapping
Epitopes
Erythrocytes
Escherichia coli
Escherichia coli Proteins
Estrus
Eukaryotic Cells
Evolution, Molecular
Exercise
Exodeoxyribonucleases
Exons
Extracellular Matrix
Extracellular Matrix Proteins
Factor VIII
Factor XIII
Female
Fetus
Fibrinogen
Fibroblasts
Fibronectins
Flow Cytometry
Fluorescein
Fluorescence
Fluorescence Polarization
Fluorescence Recovery After Photobleaching
Fluorescence Resonance Energy Transfer
Fluorescent Antibody Technique
Fluorescent Dyes
Focal Adhesions
Fourier Analysis
Fungal Proteins
GTP Phosphohydrolases
GTP-Binding Proteins
Gene Deletion
Gene Expression
Gene Expression Regulation
Gene Library
Genes, Bacterial
Genes, Insect
Genes, Reporter
Genes, src
Genetic Variation
Genetic Vectors
Glutamine
Glutaral
Glycerol
Glycoproteins
Glycosaminoglycans
Glycosides
Glycosylation
Gram-Negative Anaerobic Bacteria
Gram-Negative Bacteria
Green Fluorescent Proteins
Growth Substances
Guanine Nucleotides
Guanosine Diphosphate
Guanosine Triphosphate
Guinea Pigs
HEK293 Cells
Half-Life
HeLa Cells
Heart Ventricles
Helminth Proteins
Hematopoietic Stem Cells
Hemocyanin
Hemocyanins
Heparin
Heterozygote
Hormones
Humans
Hydrogen Bonding
Hydrogen-Ion Concentration
Hydrolysis
Image Processing, Computer-Assisted
Immune Sera
Immunoglobulin Constant Regions
Immunoglobulins
Immunohistochemistry
Immunologic Techniques
Immunoprecipitation
Inhibitory Concentration 50
Insect Proteins
Integrin alpha Chains
Integrin alphaVbeta3
Integrin beta1
Integrins
Intercellular Adhesion Molecule-1
Ion Channels
Isoenzymes
K562 Cells
Keratan Sulfate
Kinesin
Kinetics
Laminin
Lectins
Lectins, C-Type
Leukocyte L1 Antigen Complex
Leukocytes
Ligands
Light
Lipid Bilayers
Liposomes
Liver
Luminescent Proteins
Lung
Lymphocyte Function-Associated Antigen-1
Lymphocytes
Macromolecular Substances
Magnesium
Magnetic Resonance Spectroscopy
Mammary Glands, Animal
Mass Spectrometry
Mathematics
Melanocytes
Membrane Glycoproteins
Membrane Potentials
Membrane Proteins
Membranes
Mercaptoethanol
Metaphase
Methods
Mice
Mice, Inbred Strains
Mice, Knockout
Micromanipulation
Microscopy, Atomic Force
Microscopy, Electron
Microscopy, Fluorescence
Microscopy, Immunoelectron
Microspheres
Microtubule Proteins
Microtubules
Milk, Human
Mitogens
Models, Biological
Models, Chemical
Models, Genetic
Models, Molecular
Models, Structural
Models, Theoretical
Molecular Conformation
Molecular Sequence Data
Molecular Structure
Molecular Weight
Monte Carlo Method
Morphogenesis
Motion
Mucins
Multigene Family
Multiprotein Complexes
Muscle Proteins
Muscle, Skeletal
Muscles
Muscular Dystrophy, Animal
Mutagenesis
Mutagenesis, Insertional
Mutagenesis, Site-Directed
Mutation
Mycobacterium tuberculosis
Myocardium
Myosin-Light-Chain Kinase
Myosins
Negative Staining
Neoplasm Proteins
Neoplasms
Nerve Growth Factors
Nerve Tissue Proteins
Nervous System Malformations
Neural Cell Adhesion Molecules
Neurons
Neutrophils
Nuclear Magnetic Resonance, Biomolecular
Nuclear Proteins
Nucleic Acid Conformation
Octoxynol
Oligonucleotide Probes
Oligopeptides
Organ Specificity
Osmolar Concentration
Oxygen
P-Selectin
Paclitaxel
Palatine Tonsil
Peptide Fragments
Peptide Mapping
Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase
Peptides
Permeability
Phenotype
Phylogeny
Physicochemical Phenomena
Physicochemical Processes
Phytochrome
Plant Proteins
Plasmids
Plastics
Platelet Aggregation
Platelet Membrane Glycoproteins
Platelet-Derived Growth Factor
Pleurodeles
Pliability
Poly A
Polyethylene Glycols
Polymerase Chain Reaction
Polymers
Potassium
Precipitin Tests
Pregnancy
Proline
Promoter Regions, Genetic
Protein Binding
Protein Conformation
Protein Denaturation
Protein Engineering
Protein Folding
Protein Interaction Mapping
Protein Isoforms
Protein Kinases
Protein Multimerization
Protein Precursors
Protein Sorting Signals
Protein Stability
Protein Structure, Quaternary
Protein Structure, Secondary
Protein Structure, Tertiary
Protein Subunits
Protein Transport
Proteins
Proteoglycans
Proto-Oncogene Proteins pp60(c-src)
Pseudomonas aeruginosa
R Factors
RNA Splicing
RNA, Messenger
Rabbits
Radioligand Assay
Rats
Rats, Sprague-Dawley
Receptors
Receptors, Cell Surface
Receptors, Cholinergic
Receptors, Fibronectin
Receptors, Leukocyte-Adhesion
Receptors, Somatotropin
Receptors, Virus
Receptors, Vitronectin
Recombinant Fusion Proteins
Recombinant Proteins
Recombination, Genetic
Repetitive Sequences, Amino Acid
Repetitive Sequences, Nucleic Acid
Resins, Synthetic
Reticulin
Rheology
Rhinovirus
Rhodamines
Ristocetin
Rubidium
Ryanodine
Ryanodine Receptor Calcium Release Channel
Salts
Sarcoplasmic Reticulum
Scattering, Radiation
Sea Urchins
Selenomethionine
Sensitivity and Specificity
Sequence Alignment
Sequence Analysis
Sequence Analysis, DNA
Sequence Homology
Sequence Homology, Amino Acid
Serine Endopeptidases
Sertoli Cells
Signal Transduction
Silver Staining
Skin
Sodium
Solubility
Solutions
Species Specificity
Spectrometry, Fluorescence
Spectrophotometry
Spectrum Analysis
Spinal Cord
Static Electricity
Structural Homology, Protein
Structure-Activity Relationship
Succinimides
Sulfuric Acid Esters
Surface Plasmon Resonance
Surface Properties
Swine
Temperature
Tenascin
Tensile Strength
Thermodynamics
Thermolysin
Time Factors
Tissue Scaffolds
Tongue
Torsion, Mechanical
Trans-Activators
Transfection
Transforming Growth Factor beta
Transglutaminases
Trypsin
Tryptophan
Tubulin
Tumor Cells, Cultured
Ultracentrifugation
Unilamellar Liposomes
Urea
Uterus
Versicans
Vibrissae
Video Recording
Vinculin
Viral Proteins
Wound Healing
X-Ray Diffraction
X-ray crystallography
Xenopus
Xenopus Proteins
Yeasts
Zebrafish
von Willebrand Factor