Characterization of Methionine Export in Corynebacterium glutamicum

摘要: Corynebacterium glutamicum is known for its effective excretion of amino acids under particular metabolic conditions. Concomitant activities uptake and systems would create an energy-wasting futile cycle; acid export are therefore tightly regulated. We have used a DNA microarray approach to identify genes membrane proteins which overexpressed conditions elevated cytoplasmic concentrations methionine. One these was brnF, coding the larger subunit BrnFE, previously identified two-component isoleucine system. By deletion, complementation, overexpression brnFE in C. strain, two methionine were inactivated, we BrnFE as being responsible export. In presence both substrates cytoplasm, found transport at similar rates. The expression gene cluster depends on Lrp-type transcription factor shown be strongly induced by increasing concentration. Methionine better inducer than isoleucine, indicating that rather might native substrate BrnFE. When synthesis blocked chloramphenicol, fast still observed, but only greatly increased levels this acid. This indicates least one other system, presumably with low affinity high capacity. Under where does not exceed concentration 50 mM, dominant system