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J Bacteriol, May 1998, p. 2450-2458, Vol. 180, No. 9
Department of Microbiology, University of
Massachusetts, Amherst, Massachusetts 01003
Received 4 December 1997/Accepted 4 March 1998
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.
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Gas Vesicle Genes Identified in Bacillus
megaterium and Functional Expression in Escherichia
coli
*
Corresponding author. Mailing address: Department of
Microbiology, University of Massachusetts, Amherst, MA 01003. Phone: (413) 545-0092. Fax: (413) 545-1578. E-mail:
mcannon{at}bio.umass.edu.
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