Lipid hydrolizing enzymes in virulence: Mycobacterium tuberculosis as a model system.
ABSTRACT This review is focused on the virulent traits of lipolytic enzymes from bacteria with special emphasis on Mycobacterium tuberculosis. In vivo, triacylglycerols in the form of inclusion bodies are present in tubercle bacilli in the lungs. This pathogenic bacterium possesses a lipase gene (Lip) family, which is expressed and differentially regulated under a variety of in vitro conditions. Not much research work has been carried out on these lipolytic enzymes. A better understanding of lipolytic enzymes in mycobacteria would lead to develop new strategies for tuberculosis treatment. The present review highlights the recent work done in the field of mycobacterium lipolytic enzymes and their involvement in the virulence and pathogenicity.
Article: The PE-PPE domain in mycobacterium reveals a serine α/β hydrolase fold and function: an in-silico analysis.[show abstract] [hide abstract]
ABSTRACT: The PE and PPE proteins first reported in the genome sequence of Mycobacterium tuberculosis strain H37Rv are now identified in all mycobacterial species. The PE-PPE domain (Pfam ID: PF08237) is a 225 amino acid residue conserved region located towards the C-terminus of some PE and PPE proteins and hypothetical proteins. Our in-silico sequence analysis revealed that this domain is present in all Mycobacteria, some Rhodococcus and Nocardia farcinica genomes. This domain comprises a pentapeptide sequence motif GxSxG/S at the N-terminus and conserved amino acid residues Ser, Asp and His that constitute a catalytic triad characteristic of lipase, esterase and cutinase activity. The fold prediction and comparative modeling of the 3-D structure of the PE-PPE domain revealed a "serine α/β hydrolase" structure with a central β-sheet flanked by α-helices on either side. The structure comprises a lid insertion with a closed structure conformation and has a solvent inaccessible active site. The oxyanion hole that stabilizes the negative charge on the tetrahedral intermediate has been identified. Our findings add to the growing list of serine hydrolases in mycobacterium, which are essential for the maintenance of their impermeable cell wall and virulence. These results provide the directions for the design of experiments to establish the function of PE and PPE proteins.PLoS ONE 01/2011; 6(2):e16745. · 4.09 Impact Factor