SUMMARY PARAGRAPH for ABZ1
ABZ1 encodes a cytoplasmic protein (5) required for synthesis of para-aminobenzoic acid (PABA), an important component in folic acid synthesis (1, 2). Specifically, Abz1p is aminodeoxychorismate synthase (E.C. 220.127.116.11), which converts chorismate to 4-amino-4-deoxychorismate. ABZ1p resembles a fusion of the E. coli proteins pabA and pabB, which together form a complex that performs the same reaction (1). In E. coli, a third enzyme, pabC (E.C. 18.104.22.168), converts aminodeoxychorismate to PABA. Deletion of ABZ1 causes PABA auxotrophy, but mutants cultured in PABA-supplemented medium grow normally (1).
Sulfa drugs, which are often used to treat AIDS patients with opportunistic microbial infections, compete with PABA in the folic acid synthesis pathway (2). Overexpression of ABZ1 confers sulfa resistance in Saccharomyces cerevisiae (1, 2).
Last updated: 2005-08-25