A UNIQUE cre SITE CONTROLS TWO MALATE UTILIZATION OPERONS IN Enterococcus feacalis

ESPARIZ, M.; MORTERA, P.; BLANCATO, V.; SUAREZ, C.; REPIZO, G.; ALARCÓN, S. H.; MAGNI, C.

Puerto Madryn

Congreso; XLVI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

SAIB

Enterococcus faecalis is able to use malate in aerobic and anaerobicconditions. The mae locus of E. faecalis consist of two putativedivergent operons, maePE and maeKR. The first operon codifies forthe malic enzyme (MaeE) and for the malate transporter (MaeP).The second operon encodes a two component system composed bythe membrane kinase sensor (MaeK) and the transcriptionalregulator (MaeR). In a previous work we showed that inactivation ofmaeR or maeE caused complete loss of malate utilization in E.faecalis. In this communication we demonstrated that both operonsare specifically induced in response to the presence of malate in thegrowth medium and are repressed by the addition of PTS sugars. Weperformed transcriptional and mutagenesis analysis and establishedthat a unique cre site (catabolite- responsive element) locatedbetween the -14 and -27 from maePE and -76 and -89 from maeKRtranscriptional start sites governed the glucose repression of bothoperons.