Characterization of thealgCGene Expression Pattern in the Multidrug ResistantAcinetobacter baumanniiAIIMS 7 and Correlation with Biofilm Development on Abiotic Surface

Abstract

Relative quantification of algC gene expression was evaluated in the multidrug resistant strain Acinetobacter baumannii AIIMS 7 biofilm (3 to 96 h, on polystyrene surface) compared to the planktonic counterparts. Comparison revealed differential algC expression pattern with maximum 81.59-fold increase in biofilm cells versus 3.24-fold in planktonic cells (P < 0.05). Expression levels strongly correlated with specific biofilm stages (scale of 3 to 96 h), coinciding maximum at initial surface attachment stage (9 h) and biofilm maturation stage (48 h). Cloning, heterologous expression, and bioinformatics analyses indicated algC gene product as the bifunctional enzyme phosphomannomutase/phosphoglucomutase (PMM/PGM) of ∼53 kDa size, which augmented biofilms significantly in algC clones compared to controls (lacking algC gene), further localized by scanning electron microscopy. Moreover, molecular dynamics analysis on the three-dimensional structure of PMM/PGM (simulated up to 10 ns) revealed enzyme structure as stable and similar to that in P. aeruginosa (synthesis of alginate and lipopolysaccharide core) and involved in constitution of biofilm EPS (extracellular polymeric substances). Our observation on differential expression pattern of algC having strong correlation with important biofilm stages, scanning electron-microscopic evidence of biofilm augmentation taken together with predictive enzyme functions via molecular dynamic (MD) simulation, proposes a new basis of A. baumannii AIIMS 7 biofilm development on inanimate surfaces.

Comparative Proteomic Analysis Provides insight into the Key Proteins as Possible Targets Involved in Aspirin Inhibiting Biofilm Formation of Staphylococcus xylosus

“…However, based on our results, PGM expression was down-regulated in cells treated with sub-MIC aspirin compared with untreated cells. In several bacterial species, PGM is bifunctional and required for the formation of various EPSs, which play significant roles in the synthesis of active core biofilm compounds and biofilm formation ( Levander and Radstrom, 2001 ; Sahu et al, 2014 ). Specifically, the PGM enzyme is a potential drug target during biofilm-associated A. baumannii infections, as revealed by 3D structural simulation studies ( Sahu et al, 2014 ).…”

<em>Acinetobacter baumannii</em> biofilms: effects of physicochemical factors, virulence, antibiotic resistance determinants, gene regulation, and future antimicrobial treatments

“…algC is a biofilm-associated gene that mediates the synthesis of bi-functional enzyme, phosphomannomutase/phosphoglucomutase, which is required to produce exo-polysaccharide alginate and lipopolysaccharide core during biofilm formation. 144 It was reported that the expression level of algC in the MDR strain of A. baumannii was up-regulated in a biofilm mode of growth compared to a planktonic mode. 144 Characterizing the quantitative gene expression pattern (using the relative quantification method) in real-time PCR revealed that biofilm cells showed an 81.59-fold expression compared with a 3.24-fold in planktonic cells ( p <0.05).…”

“… 160 The abaR gene sequence of A. baumannii , ATCC 17978, was compared with aqsR (the LuxR-type receptor) of A. oleivorans DR1 and it was observed that the similarity to LuxR-type receptor was 80%. 144 , 145 …”

Integron-Mediated Antibiotic Resistance inAcinetobacter baumanniiIsolated from Intensive Care Unit Patients, Babol, North of Iran

“…Multidrug-resistant Acinetobacter baumannii (MDR-AB) is an important opportunistic pathogen responsible for severe hospital-acquired infections (HAIs), particularly patients admitted to the intensive care unit (ICU) [1]. MDR-AB infections especially pneumonia and bacteremia show a high mortality rate (30% to 75%) and require prolonged hospital stays in intensive care units (ICUs) [2].…”