The murF gene encodes UDP-N-acetylmuramoyl-L-alanyl-D-glutamyl-meso-2, 6-diaminopimeloyl-D-Ala-D-Ala synthetase (EC 6.3.2.15), which catalyses the final step in the synthesis of UDP-N-acetylmuramoyl-pentapeptide, the precursor of murein. An open reading frame identified as the murF gene was found in the genome of the cyanobacterium Synechocystis sp. PCC 6803. The murF gene encodes a polypeptide of 454 amino acid residues with a predicted molecular mass of 48 kDa. The murF gene is present as a single-copy gene in the genome of Synechocystis sp. PCC 6803. The amino acid sequence deduced from the murF gene is 39% identical to that of the product of the murF gene of Escherichia coli. The cyanobacterial murF gene complemented a temperature-sensitive mutation in a murF-deficient strain of E. coli, restoring the mutant's ability to synthesize a cell wall and to survive at high sublethal temperatures.