Document Detail


Pressure dependence of activity and stability of dihydrofolate reductases of the deep-sea bacterium Moritella profunda and Escherichia coli.
MedLine Citation:
PMID:  22266402     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
To understand the pressure-adaptation mechanism of deep-sea enzymes, we studied the effects of pressure on the enzyme activity and structural stability of dihydrofolate reductase (DHFR) of the deep-sea bacterium Moritella profunda (mpDHFR) in comparison with those of Escherichia coli (ecDHFR). mpDHFR exhibited optimal enzyme activity at 50MPa whereas ecDHFR was monotonically inactivated by pressure, suggesting inherent pressure-adaptation mechanisms in mpDHFR. The secondary structure of apo-mpDHFR was stable up to 80°C, as revealed by circular dichroism spectra. The free energy changes due to pressure and urea unfolding of apo-mpDHFR, determined by fluorescence spectroscopy, were smaller than those of ecDHFR, indicating the unstable structure of mpDHFR against pressure and urea despite the three-dimensional crystal structures of both DHFRs being almost the same. The respective volume changes due to pressure and urea unfolding were -45 and -53ml/mol at 25°C for mpDHFR, which were smaller (less negative) than the corresponding values of -77 and -85ml/mol for ecDHFR. These volume changes can be ascribed to the difference in internal cavity and surface hydration of each DHFR. From these results, we assume that the native structure of mpDHFR is loosely packed and highly hydrated compared with that of ecDHFR in solution.
Authors:
Eiji Ohmae; Chiho Murakami; Shin-Ichi Tate; Kunihiko Gekko; Kazumi Hata; Kazuyuki Akasaka; Chiaki Kato
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-14
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  -     ISSN:  0006-3002     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier B.V.
Affiliation:
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
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