MOSC domains: ancient, predicted sulfur-carrier domains, present in diverse metal-sulfur cluster biosynthesis proteins including Molybdenum cofactor sulfurases.

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Using computational analysis , a novel superfamily of beta -strand-rich domains was identified in the Molybdenum cofactor sulfurase and several other proteins from both prokaryotes and eukaryotes . These MOSC domains contain an absolutely conserved cysteine and occur either as stand-alone forms such as the bacterial YiiM proteins , or fused to other domains such as a NifS-like catalytic domain in Molybdenum cofactor sulfurase . The MOSC domain is predicted to be a sulfur-carrier domain that receives sulfur abstracted by the pyridoxal phosphate-dependent NifS-like enzymes , on its conserved cysteine , and delivers it for the formation of diverse sulfur-metal clusters . The identification of this domain may clarify the mechanism of biogenesis of various metallo-enzymes including Molybdenum cofactor-containing enzymes that are compromised in human type II xanthinuria .