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Computational Insights into the Mechanism of Inhibition of OASS‐A by a Small Molecule Inhibitor
Author(s) -
Bruno Agostino,
Amori Laura,
Costantino Gabriele
Publication year - 2013
Publication title -
molecular informatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.481
H-Index - 68
eISSN - 1868-1751
pISSN - 1868-1743
DOI - 10.1002/minf.201200174
Subject(s) - mechanism (biology) , chemistry , small molecule , computational biology , computer science , biology , biochemistry , epistemology , philosophy
O ‐Acetylserine sulfhydrylase (isoform A, OASS‐A) is a PLP‐dependent enzyme involved in the last step of cysteine biosynthesis in many pathogens. Many microorganisms use cysteine as the main building block for sulfur‐containing antioxidants, and cysteine depletion in several pathogens resulted in a reduced antibiotic resistance, thus leading to the identification of OASS as novel suitable molecular targets to overcome antimicrobial resistances. The precise molecular mechanism of OASS‐A inhibition by small peptides or by small molecule inhibitors is still unclear. To shed more lights on the structural basis underlying the inhibition mechanism for OASS, we engaged ourselves in studying the dynamic properties of this enzyme. In this paper, we describe a computational study involving unbiased MD simulations of OASS‐A from Haemophilus influenzae ( Hi OASS) in its inhibitor free, PLP‐bound form, and in complex with a pentapeptide inhibitor and with UPAR40, a small molecule which we have recently reported as a potent OASS‐A inhibitors. We proposed that UPAR40 inhibits Hi OASS‐A through the stabilization of a closed conformation. Moreover, preliminary docking studies and sequence analysis allow us to speculate about the non‐specificity of UPAR40 toward a particular OASS enzyme species or isoforms.