New regulatory gene that contributes to control of XXXX starch utilization genes.

@entity3404 @entity7969 @entity21840 @entity505 @entity413
@entity3404 uses starch as a source of @entity505 and energy. Early steps in the pathway of starch utilization, such as starch binding and starch hydrolysis, are encoded by sus genes, which have been characterized previously. The sus structural genes are expressed only if cells are grown in medium containing @entity7969 or higher oligomers of @entity413 . Regulation of the sus structural genes is mediated by SusR, an activator that is encoded by a gene located next to the sus structural genes. A strain with a disruption in susR cannot grow on starch but can still grow on @entity7969 and @entity21840 . A search for transposon-generated mutants that could not grow on @entity7969 and @entity21840 unexpectedly located a gene, designated malR, which regulates expression of an alpha-glucosidase not controlled by SusR. Although a disruption in susR did not affect expression of the malR controlled gene, a disruption in malR reduced expression of the sus structural genes. Thus, MalR appears to participate with SusR in regulation of the sus genes. Results of transcriptional fusion assays and reverse transcription-PCR experiments showed that malR is expressed constitutively. Moreover, multiple copies of malR provided on a plasmid (5 to 10 copies per cell) more than doubled the amount of alpha-glucosidase activity in cell extracts. Our results demonstrate that the starch utilization system of @entity3404 is controlled on at least two levels by the regulatory proteins SusR and MalR.
