Affiliation:
1. Centre for Cellular and Molecular Biology , Hyderabad, Telangana, India
Abstract
ABSTRACT
Pseudomonas syringae
possesses genes for all five major DEAD-box RNA helicases,
rhlE
,
srmB
,
csdA
,
dbpA
, and
rhlB
, that are found in γ-proteobacteria. Bioinformatic analysis of the RNA helicase genes provided detailed insights into their genomic organization, promoter characteristics, regulatory 3′ regions, and sequence similarity. Disruption of
rhlB
and
rhlE
genes did not have any effect on growth of the
P. syringae
mutants at optimum (22°C) or at low (4°C) temperatures. On the other hand, disruption of
srmB
and
dbpA
genes caused a slow-growing phenotype in the mutants at low temperature (4°C). In comparison to the above-mentioned helicases, deletion of
csdA
gene caused the mutant (Δ
csdA
) to be totally incapable of growing at 4°C while marginally affecting the growth (resulting in slow growth) at the optimum temperature (22°C). Functional complementation studies revealed that RNA helicases are functionally non-redundant, as the roles performed by different helicases are individual and specific.
IMPORTANCE
RNA metabolism is important as RNA acts as a link between genomic information and functional biomolecules, thereby playing a critical role in cellular response to environment. We investigated the role of DEAD-box RNA helicases in low-temperature adapted growth of
P. syringae
, as this group of enzymes play an essential role in modulation of RNA secondary structures. This is the first report on the assessment of all major DEAD-box RNA helicases in any Antarctic bacterium. Of the five RNA helicases, three (
srmB
,
csdA
, and
dbpA
) are important for the growth of the Antarctic
P. syringae
at low temperature. However, the requisite role of
dbpA
and the indispensable requirement of
csdA
for low-temperature adapted growth are a novel finding of this study. Growth analysis of combinatorial deletion strains was performed to understand the functional interaction among helicase genes. Similarly, genetic complementation of RNA helicase mutants was conducted for identification of gene redundancy in
P. syringae
.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Cell Biology,Microbiology (medical),Genetics,General Immunology and Microbiology,Ecology,Physiology