@article { ISI:000241414500049,
	title = {Structural and functional analysis of a conjugated bile salt hydrolase from Bifidobacterium longum reveals an evolutionary relationship with penicillin V acylase},
	journal = {Journal of Biological Chemistry},
	volume = {281},
	number = {43},
	year = {2006},
	month = {OCT},
	pages = {32516-32525},
	publisher = {AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC},
	address = {9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3996 USA},
	abstract = {<p>Bile salt hydrolase (BSH) is an enzyme produced by the intestinal microflora that catalyzes the deconjugation of glycine- or taurine-linked bile salts. The crystal structure of BSH reported here from Bifidobacterium longum reveals that it is a member of N-terminal nucleophil hydrolase structural superfamily possessing the characteristic alpha beta beta alpha tetra-lamellar tertiary structure arrangement. Site-directed mutagenesis of the catalytic nucleophil residue, however, shows that it has no role in zymogen processing into its corresponding active form. Substrate specificity was studied using Michaelis-Menten and inhibition kinetics and fluorescence spectroscopy. These data were compared with the specificity profile of BSH from Clostridium perfrigens and pencillin V acylase from Bacillus sphaericus, for both of which the three-dimensional structures are available. Comparative analysis shows a gradation in activity toward common substrates, throwing light on a possible common route toward the evolution of pencillin V acylase and BSH.</p>},
	issn = {0021-9258},
	doi = {10.1074/jbc.M604172200},
	author = {Kumar, R. Suresh and Brannigan, James A. and Prabhune, Asmita and Pundle, Archana V. and Dodson, Guy G. and Dodson, Eleanor J. and Suresh, C. G.}
}
@article { ISI:000363727100011,
	title = {Structure mediation in substrate binding and post-translational processing of penicillin acylases: Information from mutant structures of Kluyvera citrophila penicillin G acylase},
	journal = {Protein Science},
	volume = {24},
	number = {10},
	year = {2015},
	month = {OCT},
	pages = {1660-1670},
	publisher = {WILEY-BLACKWELL},
	address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA},
	abstract = {<p>Penicillin acylases are industrially important enzymes for the production of 6-APA, which is used extensively in the synthesis of secondary antibiotics. The enzyme translates into an inactive single chain precursor that subsequently gets processed by the removal of a spacer peptide connecting the chains of the mature active heterodimer. We have cloned the penicillin G acylase from Kluyvera citrophila (KcPGA) and prepared two mutants by site-directed mutagenesis. Replacement of N-terminal serine of the beta-subunit with cysteine (Ser beta 1Cys) resulted in a fully processed but inactive enzyme. The second mutant in which this serine is replaced by glycine (Ser beta 1Gly) remained in the unprocessed and inactive form. The crystals of both mutants belonged to space group P1 with four molecules in the asymmetric unit. The three-dimensional structures of these mutants were refined at resolutions 2.8 and 2.5 angstrom, respectively. Comparison of these structures with similar structures of Escherichia coli PGA (EcPGA) revealed various conformational changes that lead to autocatalytic processing and consequent removal of the spacer peptide. The large displacements of residues such as Arg168 and Arg477 toward the N-terminal cleavage site of the spacer peptide or the conformational changes of Arg145 and Phe146 near the active site in these structures suggested probable steps in the processing dynamics. A comparison between the structures of the processed Serb1Cys mutant and that of the processed form of EcPGA showed conformational differences in residues Arg alpha 145, Phe alpha 146, and Phe beta 24 at the substrate binding pocket. Three conformational transitions of Arg alpha 145 and Phe alpha 146 residues were seen when processed and unprocessed forms of KcPGA were compared with the substrate bound structure of EcPGA. Structure mediation in activity difference between KcPGA and EcPGA toward acyl homoserine lactone (AHL) is elucidated.</p>},
	keywords = {acyl homoserine lactone, autocatalytic processing, conformational changes, KcPGA_Ser beta 1Cys, KcPGA_Ser beta 1Gly, Ntn hydrolase},
	issn = {0961-8368},
	doi = {10.1002/pro.2761},
	author = {Chand, Deepak and Varshney, NishantKumar and Ramasamy, Sureshkumar and Panigrahi, Priyabrata and Brannigan, James A. and Wilkinson, Anthony J. and Suresh, C. G.}
}
