The levels of exoamylase and other exoenzymes of are pleiotropically decreased by the and mutations. These mutations also cause a competence- and sporulation-deficient phenotype. In the present work, the ecs locus, which has been defined by the and mutations, was cloned and sequenced. Sequence analysis revealed a putative operon of three ORFs and can encode a putative polypeptide of 248 amino acid residues containing an ATP-binding site. The polypeptide shows about 30% sequence similarity with the ATP-binding components of numerous membrane transporters of the ABC-type (ATP-binding cassette transporters or traffic ATPases). The mutation was found to result from a transition of one base pair changing the glycine of EcsA to a glutamic acid residue in the vicinity of the putative ATP-binding pocket. was predicted to encode a hydrophobic protein with six membrane-spanning helices in a pattern found in other hydrophobic components of ABC transporters. The properties deduced for the and gene products are consistent with the interpretation that encodes a novel ABC-type membrane transporter of The third ORF, can encode a putative polypeptide of 237 amino acid residues. The polypeptide does not resemble components of ABC transporters.


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