Functions of S-layers.
Although S-layers are being increasingly identified on Bacteria and Archaea, it is enigmatic that in most cases S-layer function continues to elude us. In a few instances, S-layers have been shown to be virulence factors on pathogens (e.g. Campylobacter fetus ssp. fetus and Aeromonas salmonicida), protective against Bdellovibrio, a depository for surface-exposed enzymes (e.g. Bacillus stearothermophilus), shape-determining agents (e.g. Thermoproteus tenax) and nucleation factors for fine-grain mineral development (e.g. Synechococcus GL 24). Yet, for the vast majority of S-layered bacteria, the natural function of these crystalline arrays continues to be evasive. The following review up-dates the functional basis of S-layers and describes such diverse topics as the effect of S-layers on the Gram stain, bacteriophage adsorption in lactobacilli, phagocytosis by human polymorphonuclear leukocytes, the adhesion of a high-molecular-mass amylase, outer membrane porosity, and the secretion of extracellular enzymes of Thermoanaerobacterium. In addition, the functional aspect of calcium on the Caulobacter S-layer is explained.
Beveridge
T J
TJ
Department of Microbiology, College of Biological Science, University of Guelph, Canada. tjb@micro.uoguelph.ca
Pouwels
P H
PH
Sára
M
M
Kotiranta
A
A
Lounatmaa
K
K
Kari
K
K
Kerosuo
E
E
Haapasalo
M
M
Egelseer
E M
EM
Schocher
I
I
Sleytr
U B
UB
Morelli
L
L
Callegari
M L
ML
Nomellini
J F
JF
Bingle
W H
WH
Smit
J
J
Leibovitz
E
E
Lemaire
M
M
Miras
I
I
Salamitou
S
S
Béguin
P
P
Ohayon
H
H
Gounon
P
P
Matuschek
M
M
Koval
S F
SF
D000034:Abortion, Veterinary / Q000276:immunology / Q000382:microbiology; D000595:Amino Acid Sequence; D000818:Animals; D001105:Archaea / Q000502:physiology / Q000648:ultrastructure; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000648:ultrastructure; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology*; D018407:Bacterial Physiological Phenomena; D002169:Campylobacter Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D002473:Cell Wall / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D003460:Crystallization; D056890:Eukaryota / Q000502:physiology; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D010587:Phagocytosis; D011247:Pregnancy; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology / Q000382:microbiology; D013045:Species Specificity; D014774:Virulence
D001425:Bacterial Outer Membrane Proteins