A genomic and functional appraisal of the twin arginine translocation system in intracellular bacteria

NUÑEZ P; MORETTA R; SORIA M; FARBER M

Carloz Paz, Cordoba

Congreso; SAIB; 2008

SAIB

A GENOMIC AND FUNCTIONAL APPRAISAL OF TWIN-ARGININE TRANSLOCATION SYSTEM IN INTRACELLULAR BACTERIA NUÑEZ P1, MORETTA R1, SORIA M2, FARBER M1 1Biotechnology Institute, National Institute of Agricultural Technology (INTA), Buenos Aires, Argentina, e_mail: pnunez@cnia.inta.gov.ar 2Microbiology, Faculty of Agronomy, University of Buenos Aires The TAT system is a novel protein transport complex that target folded proteins across the inner membrane of gram negative bacteria. Tat membrane components, tatA, B, and C have been identified in most of the bacterial sequenced genomes. However the extent to which this secretory pathway is utilized is not well characterized. Comparative genomic analysis throughout alphaproteobacteria confirmed the presence of tatA, B, and C in almost all studied genomes. Synteny analyses allow us to split the class in two groups with either operon or scattered organization. qRT-PCR assays using A. marginale and B. abortus RNA were performed to confirmed expression and determine the stoichiometric ratio of tatABC mRNA so as to characterize transcriptional regulation mechanism. The ability of tatABC genes to compensate for the absence of the cognate E. coli one was attained. Furthermore, a genome wide identification of putative tat substrates among alphaproteobacteria was performed using TatFIND1.4. Since some organisms appear to make extensive use of this pathway, others seem to secrete very few products through it. GO terms and clustering analysis led to the classification of the organism into groups regarding to the properties and number of predicted substrates. Whether or not this classification could be in accordance to adaptive mechanism for very different ecological niches will be discussed.