The invariant F283 and its strategic position in the hydrophobic cleft of Streptomyces jumonjinensis isopenicillin N synthase active site are functionally important

Isopenicillin N synthase (IPNS) and related non-haem iron-binding enzymes i ncluding deacetoxycephalosporin C synthase (DAOCS) are proposed to have str ucturally similar active centers. Sequence alignment and computational stru ctural analyses of predicted structures revealed 11 highly conserved hydrop hobic amino acid residues in 134 IPNS-related enzymes form a contiguous hyd rophobic patch in the IPNS active center, wherein F283 is strategically pos itioned. The investigation of single and double mutations at F283, adjacent (L284) and proximal sites (N285 and S216) of Streptomyces jumonjinensis IP NS advocate the explicit importance of the phenyl ring at position 283. A s imilarly placed phenylalanine (F264) in DAOCS was found to be also crucial for its enzyme activity. (C) 2001 Academic Press.