Affiliation:
1. Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003
Abstract
ABSTRACT
Gas vesicles are intracellular, protein-coated, and hollow organelles found in cyanobacteria and halophilic archaea. They are permeable to ambient gases by diffusion and provide buoyancy, enabling cells to move upwards in liquid to access oxygen and/or light. In halobacteria, gas vesicle production is encoded in a 9-kb cluster of 14 genes (4 of known function). In cyanobacteria, the number of genes involved has not been determined. We now report the cloning and sequence analysis of an 8,142-bp cluster of 15 putative gas vesicle genes (
gvp
) from
Bacillus megaterium
VT1660 and their functional expression in
Escherichia coli
. Evidence includes homologies by sequence analysis to known gas vesicle genes, the buoyancy phenotype of
E. coli
strains that carry this
gvp
gene cluster, the presence of pressure-sensitive, refractile bodies in phase-contrast microscopy, structural details in phase-constrast microscopy, structural details in direct interference-contrast microscopy, and shape and size revealed by transmission electron microscopy. In
B. megaterium
, the
gvp
region carries a cluster of 15 putative genes arranged in one orientation; they are open reading frame 1 and
gvpA
, -
P
, -
Q
, -
B
, -
R
, -
N
, -
F
, -
G
, -
L
, -
S
, -
K
, -
J
, -
T
, and -
U
, of which the last 11 genes, in a 5.7-kb gene cluster, are the maximum required for gas vesicle synthesis and function in
E. coli
. To our knowledge, this is the first example of a functional gas vesicle gene cluster in nonaquatic bacteria and the first example of the interspecies transfer of genes resulting in the synthesis of a functional organelle.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology