1.Structure mediation in substrate binding and post-translational processing of penicillin acylases: Information from mutant structures of Kluyvera citrophila penicillin G acylase.
Chand D1, Varshney N1, Ramasamy S1, Panigrahi P1, Brannigan JA2, Wilkinson AJ2, Suresh CG1. Protein Sci. 2015 Oct;24(10):1660-70. doi: 10.1002/pro.2761. Epub 2015 Aug 17.
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 β-subunit with cysteine (Serβ1Cys) resulted in a fully processed but inactive enzyme. The second mutant in which this serine is replaced by glycine (Serβ1Gly) 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 Å, 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.
2.Interference of Quorum Sensing by Delftia sp. VM4 Depends on the Activity of a Novel N-Acylhomoserine Lactone-Acylase.
Maisuria VB1, Nerurkar AS2. PLoS One. 2015 Sep 18;10(9):e0138034. doi: 10.1371/journal.pone.0138034. eCollection 2015.
BACKGROUND: Turf soil bacterial isolate Delftia sp. VM4 can degrade exogenous N-acyl homoserine lactone (AHL), hence it effectively attenuates the virulence of bacterial soft rot pathogen Pectobacterium carotovorum subsp. carotovorum strain BR1 (Pcc BR1) as a consequence of quorum sensing inhibition.
3.MomL, a novel marine-derived N-acyl homoserine lactonase from Muricauda olearia.
Tang K1, Su Y1, Brackman G2, Cui F1, Zhang Y1, Shi X1, Coenye T2, Zhang XH3. Appl Environ Microbiol. 2015 Jan;81(2):774-82. doi: 10.1128/AEM.02805-14. Epub 2014 Nov 14.
Gram-negative bacteria use N-acyl homoserine lactones (AHLs) as quorum sensing (QS) signaling molecules for interspecies communication, and AHL-dependent QS is related with virulence factor production in many bacterial pathogens. Quorum quenching, the enzymatic degradation of the signaling molecule, would attenuate virulence rather than kill the pathogens, and thereby reduce the potential for evolution of drug resistance. In a previous study, we showed that Muricauda olearia Th120, belonging to the class Flavobacteriia, has strong AHL degradative activity. In this study, an AHL lactonase (designated MomL), which could degrade both short- and long-chain AHLs with or without a substitution of oxo-group at the C-3 position, was identified from Th120. Liquid chromatography-mass spectrometry analysis demonstrated that MomL functions as an AHL lactonase catalyzing AHL degradation through lactone hydrolysis. MomL is an AHL lactonase belonging to the metallo-β-lactamase superfamily that harbors an N-terminal signal peptide.
4.Antimicrobial properties of Kalanchoe blossfeldiana: a focus on drug resistance with particular reference to quorum sensing-mediated bacterial biofilm formation.
Sarkar R1,2, Mondal C1, Bera R3, Chakraborty S1, Barik R3, Roy P1, Kumar A1, Yadav KK1, Choudhury J4, Chaudhary SK2, Samanta SK5, Karmakar S1,2, Das S6, Mukherjee PK1,2, Mukherjee J4, Sen T1,2. J Pharm Pharmacol. 2015 Jul;67(7):951-62. doi: 10.1111/jphp.12397. Epub 2015 Apr 1.
OBJECTIVES: This study attempts to investigate the antimicrobial properties of Kalanchoe blossfeldiana with a particular reference to quorum sensing (QS)-mediated biofilm formation.
