Crystal structure of a trimeric archaeal adenylate kinase from the mesophile Methanococcus maripaludis with an unusually broad functional range and thermal stability |
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Authors: | Milya Davlieva Yousif Shamoo |
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Affiliation: | Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005‐1892 |
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Abstract: | The structure of the trimeric adenylate kinase from the Archaebacteria Methanococcus mariplaludis (AKMAR) has been solved to 2.5‐Å resolution and the temperature dependent stability and kinetics of the enzyme measured. The KM and Vmax of AKMAR exhibit only modest temperature dependence from 30°–60°C. Although M. mariplaludis is a mesophile with a maximum growth temperature of 43°C, AKMAR has a very broad functional range and stability (Tm = 74.0°C) that are more consistent with a thermophilic enzyme with high thermostability and exceptional activity over a wide range of temperatures, suggesting that this microbe may have only recently invaded a mesophilic niche and has yet to fully adapt. A comparison of the Local Structural Entropy (LSE) for AKMAR to the related adenylate kinases from the mesophile Methanococcus voltae and thermophile Methanococcus thermolithotrophicus show that changes in LSE are able to fully account for the intermediate stability of AKMAR and highlights a general mechanism for protein adaptation in this class of enzymes. Proteins 2010. © 2009 Wiley‐Liss, Inc. |
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Keywords: | phosphotransferase Archaebacteria nucleoside monophosphate kinases X‐ray crystallography enzyme kinetics thermal unfolding |
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