Proteomic Analysis of Bacterial Expression Profiles Following Exposure to Organic Solvent Flower Extract of &lt;i&gt;Melastoma candidu&lt;/i&gt;m D Don (Melastomataceae)

F-C Wong,A-L Yong,T-T Chai,K-M Sim,H-C Ong

doi:10.4314/tjpr.v13i7.11

Abstract

Purpose: To identify potential antibacterial protein targets following exposure to Melastoma candidum extract.Methods: Plant extracts were prepared using sequential extraction method. Denaturing gel electrophoresis and MALDI TOF-TOF MS protein sequencing were used to identify differentialexpressed bacterial proteins. 96-well microplate method was used to determine the minimum inhibitory concentration (MIC) values. Thin layer chromatography (TLC) bio-autobiography and gaschromatography-mass spectrometry (GC-MS) were performed to determine the phytochemicals in the active fraction.Results: Five differentially expressed bacterial proteins (four from Escherichia coli and one from Staphylococcus aureus), were identified via proteomic approach. Among the bacterial proteins identified, glutamate decarboxylase, elongation factor-Tu and α-hemolysin are especially noteworthy, as they are implicated in critical bacterial pathways pertaining to survival in acidic environment, protein translation and virulence, respectively. Additionally, we tested and reported the minimum inhibition concentrations of different M. candidum fractions and gas chromatography-mass spectrometry GC-MS analysis of the active fraction.Conclusion: Glutamate decarboxylase, elongation factor-Tu and α-hemolysin represent potential antibacterial targets.Keywords: Escherichia coli, Staphylococcus aureus, Melastoma candidum, Glutamate decarboxylase, Elongation factor-Tu, α-Hemolysin, Protein expression

Highlights

As the world is facing increasing cases of multidrug-resistant bacteria, there is an urgent need to search for novel antibacterial compounds
Using proteomic analysis methods, differentially expressed proteins have been identified in Gram-positive Staphylococcus aureus following exposure to silver (Ag), an active antibacterial agent incorporated in many healthcare products [3]
We identified and reported five differentially expressed bacterial proteins, following exposure to M. candidum extracts

Summary

Introduction

As the world is facing increasing cases of multidrug-resistant bacteria, there is an urgent need to search for novel antibacterial compounds. Potential sources of antibacterial compounds include those derived from natural products such as medicinal plants. The inhibition mechanisms of many antibacterial phytochemicals remain elusive. It is unclear which bacterial pathways or enzymes are being targeted. Trop J Pharm Res, July 2014; 13(7):1085 effects of antibacterial agents on bacterial gene expressions [1,2]. Using proteomic analysis methods, differentially expressed proteins have been identified in Gram-positive Staphylococcus aureus following exposure to silver (Ag), an active antibacterial agent incorporated in many healthcare products [3]. A similar approach has been applied using plumbagin, an antimicrobial compound found in many medicinal plants [4]. Differentially expressed proteins from Gram-negative Escherichia coli have been pinpointed

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