Journal:Acta Cryst D:S2059798322001772
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| - | <StructureSection load='' size='450' side='right' scene=' | + | <StructureSection load='' size='450' side='right' scene='90/906221/Cv1/1' caption=''> |
===Crystal structure of the putative cell wall lipoglycan biosynthesis protein LmcA from ''Mycobacterium smegmatis''=== | ===Crystal structure of the putative cell wall lipoglycan biosynthesis protein LmcA from ''Mycobacterium smegmatis''=== | ||
<big>Onisha Patel, Rajini Brammananth, Weiwen Dai, Santosh Panjikar, Ross L. Coppel, Isabelle S. Lucet and Paul K. Crellin</big> <ref>doi: 10.1107/S2059798322001772</ref> | <big>Onisha Patel, Rajini Brammananth, Weiwen Dai, Santosh Panjikar, Ross L. Coppel, Isabelle S. Lucet and Paul K. Crellin</big> <ref>doi: 10.1107/S2059798322001772</ref> | ||
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The bacterium ''Mycobacterium tuberculosis'' infects one-quarter of the entire human population, resulting in more than a million deaths from Tuberculosis each year. In their cell walls, Mycobacteria synthesize abundant, related cell wall glycolipids called phosphatidyl-''myo''-inositol mannosides (PIMs), lipomannans (LMs) and lipoarabinomannans (LAMs), which interact with the infected host. This paper describes the first crystal structure of LmcA, a recently identified Mycobacterial protein that converts PIMs into LMs and LAMs, via an unknown mechanism. | The bacterium ''Mycobacterium tuberculosis'' infects one-quarter of the entire human population, resulting in more than a million deaths from Tuberculosis each year. In their cell walls, Mycobacteria synthesize abundant, related cell wall glycolipids called phosphatidyl-''myo''-inositol mannosides (PIMs), lipomannans (LMs) and lipoarabinomannans (LAMs), which interact with the infected host. This paper describes the first crystal structure of LmcA, a recently identified Mycobacterial protein that converts PIMs into LMs and LAMs, via an unknown mechanism. | ||
| - | The LmcA structure revealed an elongated beta-barrel fold and one alpha-helix extending away from the beta-barrel core. Interestingly, two distinct cavities were found inside the protein which could bind a ligand. Further analysis revealed elements in LmcA that may undergo conformational changes to ‘open’ the protein, permitting access to the cavities. While the ligand remains to be identified, comparison of the crystal structure with LmcA models from other bacterial species suggests a common mechanism of ligand binding involving the cavities. These findings provide new structural insights into the biosynthetic pathway for PIM/LM/LAM, essential components of the mycobacterial cell surface. | + | The LmcA structure revealed an elongated beta-barrel fold and one alpha-helix extending away from the beta-barrel core. <scene name='90/906221/Cv/7'>The crystal structure of MSMEG_0317</scene> adopts an extended beta-barrel core composed of 11 antiparallel beta-strands with two alpha-turns and one alpha-helix extending away from the core. The secondary structure elements are shown in distinct colours. Interestingly, <scene name='90/906221/Cv/20'>two distinct cavities</scene> were found inside the protein which could bind a ligand. Further analysis revealed elements in LmcA that may undergo conformational changes to ‘open’ the protein, permitting access to the cavities. <scene name='90/906221/Cv4/6'>Comparison of MSMEG_0317 (white) with MSMEG_0317-Xe (pink) highlights changes in loop 9 conformation to a more "open" state due to xenon binding</scene>. <jmol><jmolButton> |
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| + | </jmolButton></jmol> <scene name='90/906221/Cv4/7'>This scene without animation</scene>. While the ligand remains to be identified, comparison of the crystal structure with LmcA models from other bacterial species suggests a common mechanism of ligand binding involving the cavities. These findings provide new structural insights into the biosynthetic pathway for PIM/LM/LAM, essential components of the mycobacterial cell surface. | ||
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| + | '''PDB references:''' MSMEG_0317Δ, [[7n3v]]; xenon derivative, [[7shw]]. | ||
<b>References</b><br> | <b>References</b><br> | ||
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