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Title: The Mycobacterium tuberculosis desaturase DesA1 (Rv0824c) is a Ca{sup 2+} binding protein

Abstract

The hallmark feature of Mycobacterium tuberculosis (M.tb) the causative agent of human tuberculosis, is its complex lipid rich cell wall comprised primarily of mycolic acids, long chain fatty acids that play a key role in structural stability and permeability of the cell wall. In addition, they are involved in inhibiting phagosome-lysosome fusion and aid in granuloma formation during the pathogenic process. M.tb DesA1 is an essential acyl-acyl carrier protein desaturase predicted to catalyze the introduction of position specific double bonds during the biosynthesis of mycolic acids. This protein is one among three annotated desaturases (DesA1-3) in the M.tb genome but is unique in containing a βγ-crystallin Greek key signature motif, a well-characterized fold known to mediate Ca{sup 2+} binding in both prokaryotic and eukaryotic organisms. Using Isothermal Titration Calorimetry and {sup 45}CaCl{sub 2} overlay, we demonstrate that Ca{sup 2+} binds to DesA1. Spectroscopic measurements suggested that this binding induces changes in protein conformation but does not lead to significant alterations in the secondary structure of the protein, a feature common to several βγ-crystallins. An M. smegmatis strain over-expressing M.tb desA1 showed a Ca{sup 2+} dependent variation in surface phenotype, revealing a functional role for Ca{sup 2+}in DesA1 activity. This studymore » represents the first identification of a Ca{sup 2+} binding βγ-crystallin in M.tb, emphasizing the implicit role of Ca{sup 2+} in the pathogenesis of M.tb. - Highlights: • Mycobacterium tuberculosis DesA1 is an essential acyl-ACP desaturase. • DesA1 was identified to contain a βγ-crystallin Greek key signature motif. • Ca{sup 2+} binds to DesA1 with an affinity of 53 μM and induces changes in its conformation. • M. smegmatis overexpressing M.tb DesA1 shows a Ca{sup 2+} dependent phenotype. • Targetting the Ca{sup 2+} dependent function of DesA1 could be of therapeutic value.« less

Authors:
; ; ; ; ;
Publication Date:
OSTI Identifier:
22696675
Resource Type:
Journal Article
Journal Name:
Biochemical and Biophysical Research Communications
Additional Journal Information:
Journal Volume: 480; Journal Issue: 1; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0006-291X
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; CALCIUM IONS; CARBOXYLIC ACIDS; CELL WALL; DOUBLE BONDS; MYCOBACTERIUM TUBERCULOSIS

Citation Formats

Yeruva, Veena C., E-mail: veenachaitanya@ccmb.res.in, Savanagouder, Mamata, Khandelwal, Radhika, Kulkarni, Apoorva, Sharma, Yogendra, and Raghunand, Tirumalai R., E-mail: raghu@ccmb.res.in. The Mycobacterium tuberculosis desaturase DesA1 (Rv0824c) is a Ca{sup 2+} binding protein. United States: N. p., 2016. Web. doi:10.1016/J.BBRC.2016.10.014.
Yeruva, Veena C., E-mail: veenachaitanya@ccmb.res.in, Savanagouder, Mamata, Khandelwal, Radhika, Kulkarni, Apoorva, Sharma, Yogendra, & Raghunand, Tirumalai R., E-mail: raghu@ccmb.res.in. The Mycobacterium tuberculosis desaturase DesA1 (Rv0824c) is a Ca{sup 2+} binding protein. United States. doi:10.1016/J.BBRC.2016.10.014.
Yeruva, Veena C., E-mail: veenachaitanya@ccmb.res.in, Savanagouder, Mamata, Khandelwal, Radhika, Kulkarni, Apoorva, Sharma, Yogendra, and Raghunand, Tirumalai R., E-mail: raghu@ccmb.res.in. Fri . "The Mycobacterium tuberculosis desaturase DesA1 (Rv0824c) is a Ca{sup 2+} binding protein". United States. doi:10.1016/J.BBRC.2016.10.014.
@article{osti_22696675,
title = {The Mycobacterium tuberculosis desaturase DesA1 (Rv0824c) is a Ca{sup 2+} binding protein},
author = {Yeruva, Veena C., E-mail: veenachaitanya@ccmb.res.in and Savanagouder, Mamata and Khandelwal, Radhika and Kulkarni, Apoorva and Sharma, Yogendra and Raghunand, Tirumalai R., E-mail: raghu@ccmb.res.in},
abstractNote = {The hallmark feature of Mycobacterium tuberculosis (M.tb) the causative agent of human tuberculosis, is its complex lipid rich cell wall comprised primarily of mycolic acids, long chain fatty acids that play a key role in structural stability and permeability of the cell wall. In addition, they are involved in inhibiting phagosome-lysosome fusion and aid in granuloma formation during the pathogenic process. M.tb DesA1 is an essential acyl-acyl carrier protein desaturase predicted to catalyze the introduction of position specific double bonds during the biosynthesis of mycolic acids. This protein is one among three annotated desaturases (DesA1-3) in the M.tb genome but is unique in containing a βγ-crystallin Greek key signature motif, a well-characterized fold known to mediate Ca{sup 2+} binding in both prokaryotic and eukaryotic organisms. Using Isothermal Titration Calorimetry and {sup 45}CaCl{sub 2} overlay, we demonstrate that Ca{sup 2+} binds to DesA1. Spectroscopic measurements suggested that this binding induces changes in protein conformation but does not lead to significant alterations in the secondary structure of the protein, a feature common to several βγ-crystallins. An M. smegmatis strain over-expressing M.tb desA1 showed a Ca{sup 2+} dependent variation in surface phenotype, revealing a functional role for Ca{sup 2+}in DesA1 activity. This study represents the first identification of a Ca{sup 2+} binding βγ-crystallin in M.tb, emphasizing the implicit role of Ca{sup 2+} in the pathogenesis of M.tb. - Highlights: • Mycobacterium tuberculosis DesA1 is an essential acyl-ACP desaturase. • DesA1 was identified to contain a βγ-crystallin Greek key signature motif. • Ca{sup 2+} binds to DesA1 with an affinity of 53 μM and induces changes in its conformation. • M. smegmatis overexpressing M.tb DesA1 shows a Ca{sup 2+} dependent phenotype. • Targetting the Ca{sup 2+} dependent function of DesA1 could be of therapeutic value.},
doi = {10.1016/J.BBRC.2016.10.014},
journal = {Biochemical and Biophysical Research Communications},
issn = {0006-291X},
number = 1,
volume = 480,
place = {United States},
year = {2016},
month = {11}
}