XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Posters
31.
CHaraCTERIZATION OF a GENE ENCODING a SMALL REGULATORY RPOE
– DEPENDENT RNA IN SALMoneLLA enTerICA SEROvar TYPHIMURIUM
Dagmar Homerová, Bronislava Řežuchová, Henrieta Škovierová and Ján Kormanec
Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava
Gene regulation of bacteria is a complex process in which proteins have been believed
as the only relevant regulators for a long time. In recent years, the family of small noncoding
RNA (sRNA) with the important role especially in post-transcription control
was described. Enterobacterial pathogen Salmonella enterica serovar Typhimurium
(S. Typhimurium) is an attractive model for studying sRNAs, since the research could
clarify many processes affecting the regulation of bacterial pathogenicity. So far, more
than 70 sRNAs with various roles in control of gene expression have been identified in S.
Typhimurium. Among them, small antisense RNA MicA, activated by sigma factor RpoE,
strongly represses the mRNAs of two porins, OmpA and LamB. To understand the role
of MicA we have investigated its expression and role in virulence of S. Typhimurium. In
vitro transcriptional analysis revealed presence of a single promoter, micAp, with the
high similarity with the consensus RpoE promoter sequence showing clear dependence
upon this sigma factor. Activity of micAp increased towards stationary phase and was
induced by several stresses including heat shock, cold shock, acid stress, oxidative stress,
ethanol, polymixin B, and by degS-specific stress elicited by unfolded C-terminal outer
membrane protein OmpA. Lack of micA elicited an RpoE-dependent envelope stress
response. Although in vitro phenotypic analysis revealed no significant differences between
wild type and micA mutant strains, in vivo studies showed that the micA mutant
is more virulent in the mouse model.
Ackowledgement: This work was supported by the VEGA grant 2/0104/09 from Slovak
Academy of Sciences.
XXII. Biochemistry Congress, Martin
149