Affiliation:
1. Department of Microbiology, The University of Iowa, Iowa City, Iowa
Abstract
ABSTRACT
Flagella act as semirigid helical propellers that are powered by reversible rotary motors. Two membrane proteins, MotA and MotB, function as a complex that acts as the stator and generates the torque that drives rotation. The genome sequence of
Pseudomonas aeruginosa
PAO1 contains dual sets of
motA
and
motB
genes, PA1460-PA1461 (
motAB
) and PA4954-PA4953 (
motCD
), as well as another gene,
motY
(PA3526), which is known to be required for motor function in some bacteria. Here, we show that these five genes contribute to motility. Loss of function of either
motAB
-like locus was dispensable for translocation in aqueous environments. However, swimming could be entirely eliminated by introduction of combinations of mutations in the two
motAB
-encoding regions. Mutation of both genes encoding the MotA homologs or MotB homologs was sufficient to abolish motility. Mutants carrying double mutations in nonequivalent genes (i.e.,
motA motD
or
motB motC
) retained motility, indicating that noncognate components can function together.
motY
appears to be required for
motAB
function. The combination of
motY
and
motCD
mutations rendered the cells nonmotile. Loss of function of
motAB
,
motY
, or
motAB motY
produced similar phenotypes; although the swimming speed was only reduced to ∼85% of the wild-type speed, translocation in semisolid motility agar and swarming on the surface of solidified agar were severely impeded. Thus, the flagellar motor of
P. aeruginosa
represents a more complex configuration than the configuration that has been studied in other bacteria, and it enables efficient movement under different circumstances.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
122 articles.
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