”Identification, distribution and regulation of phlaea, a type-a phospholipase from E. Aerogenes”

FEDRIGO, GRISELDA VALERIA; ALTABE, SILVIA; CASTELLI, MARÍA EUGENIA; GARCÍA VÉSCOVI, ELEONORA

Rosario

Congreso; Reunión anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular, Rosario

IDENTIFICATION, DISTRIBUTION AND REGULATION OF PhlAEa, A TYPE-A PHOSPHOLIPASE FROM E. aerogenes Fedrigo, Griselda V.; Altabe, Silvia; Castelli, María E. and García Véscovi, Eleonora IBR-CONICET, Fac. de Cs. Bioq y Farm,UNR. Suipacha 531, 2000 Rosario, Argentina. E-mail: fedrigo@ibr.gov.ar Enterobacter is an opportunistic pathogen associated to nosocomial infections. We selected an E. aerogenes isolate from an Enterobacter clinical collection strain that exhibited marked extracellular lipolytic activity. We identified that this exoprotein corresponded to a type A phospholipase (phlAEa) with high homology to phospholipases present in Serratia, Yersinia, Xanthomonas and Photorhabdus (E. aerogenes has no available genome database). By sourthern-blot analysis we showed that this locus was present only in some strains of our Enterobacter collection suggesting that this genomic region was subjected to DNA rearrangement processes. We determined the transcription initiation site for phlAEa by primer extention. The putative phlAEa promoter region showed sequences that matched to predicted cAMP-CRP and sF recognition motifs. We analyzed phlAEa expression by measuring lypolitic activity and transcriptional regulation by β-galactosidase activity from a phlAEa::lacZ fusion. We observed that phlAEa expression was regulated by catabolite repression and induced when bacteria were grown at 30ºC. phlAEa transcriptional levels were abolished in an E. coli flhD strain consistent with the sF-regulatory-dependence. In addition we showed that the expression of the flagella was required for PhlAEa to be exported.