The Bacillus subtilis cell-division 135-137 degrees region contains an essential orf with significant similarity to murB and a dispensable sbp gene.

Sequence similarity analysis has revealed that orf2, in the cell division 135-137 degrees region of the Bacillus subtilis (Bs) chromosome, is the probable homolog of Escherichia coli murB (encoding a reductase involved in peptidoglycan synthesis). The amino-acid sequences of the two protein products show 24% identity (47% overall similarity), with several regions of higher similarity which may represent functional domains of the proteins. Attempts to insertionally inactivate orf2 were unsuccessful, strongly suggesting that it is an essential Bs gene. A small gene found in the same region as orf2, sbp (encoding the 'small basic protein'), was shown to be non-essential in Bs.