tailieunhanh - Báo cáo khoa hoc : Structural basis of the inhibition of class C acid phosphatases by adenosine 5¢-phosphorothioate

The inhibition of phosphatases by adenosine 5¢-phosphorothioate (AMPS) was first reported in the late 1960s; however, the structural basis for the inhibition has remained unknown. Here, it is shown that AMPS is a submi-cromolar inhibitor of class C acid phosphatases | IFEBS Journal Structural basis of the inhibition of class C acid phosphatases by adenosine 5 -phosphorothioate Harkewal Singh1 Thomas J. Reilly2 and John J. Tanner1 3 1 Department of Chemistry University of Missouri-Columbia MO USA 2 Department of Veterinary Pathobiology and Veterinary MedicalDiagnostic Laboratory University of Missouri-Columbia MO USA 3 Department of Biochemistry University of Missouri-Columbia MO USA Keywords adenosine 5 -phosphorothioate class C acid phosphatase enzyme inhibition substrate recognition X-ray crystallography Correspondence J. J. Tanner Department of Chemistry University of Missouri-Columbia Columbia MO 65211 USA Fax 1 573 882 2754 Tel 1 573 884 1280 E-mail tannerjj@ Received 3 August 2011 revised 13 September 2011 accepted 15 September 2011 doi The inhibition of phosphatases by adenosine 5 -phosphorothioate AMPS was first reported in the late 1960s however the structural basis for the inhibition has remained unknown. Here it is shown that AMPS is a submicromolar inhibitor of class C acid phosphatases a group of bacterial outer membrane enzymes belonging to the haloacid dehalogenase structural superfamily. Furthermore the resolution crystal structure of the inhibited recombinant Haemophilus influenzae class C acid phosphatase was determined this is the first structure of a phosphatase complexed with AMPS. The conformation of AMPS is identical to that of the substrate 5 -AMP except that steric factors force a rotation of the thiophosphoryl out of the normal phosphoryl-binding pocket. This conformation is catalytically nonproductive because the P atom is not positioned optimally for nucleophilic attack by Asp64 and the O atom of the scissile O-P bond is too far from the Asp Asp66 that protonates the leaving group. The structure of 5 -AMP complexed with the Asp64 fi Asn mutant enzyme was also determined at resolution. This mutation induces the substrate to adopt the same .