Skip Navigation



MBE Advance Access published online on August 18, 2004
Molecular Biology and Evolution, doi:10.1093/molbev/msh237
Molecular Biology and Evolution © Society for Molecular Biology and Evolution 2004; all rights reserved
This Article
Right arrow Advance Access manuscript (PDF) Freely available
Right arrow All Versions of this Article:
21/12/2246    most recent
msh237v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Fields, P. A.
Right arrow Articles by Houseman, D. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fields, P. A.
Right arrow Articles by Houseman, D. E.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Accepted August 10, 2004

Original Article

Decreases in Activation Energy and Substrate Affinity in Cold Adapted A4-Lactate Dehydrogenase: Evidence from the Antarctic Notothenioid Fish Chaenocephalus Aceratus

Peter A. Fields 1* Daniel E. Houseman 2

1 Biology Department, Franklin and Marshall College, Lancaster, Pennsylvania USA 17604-3003 (current affiliation); Hopkins Marine Station of Stanford University, Pacific Grove, California USA
2 Biology Department, Franklin and Marshall College, Lancaster, Pennsylvania USA 17604-3003 (current affiliation)

* To whom correspondence should be addressed. E-mail: peter.fields{at}fandm.edu.


  Abstract

Enzyme function is strongly affected by temperature, and orthologs from species adapted to different thermal environments often show temperature compensation in kinetic properties. Antarctic notothenioid fishes live in a habitat of constant, extreme cold (-1.86 - +2°C), and orthologs of the enzyme A4-lactate dehydrogenase (A4-LDH) in these species have adapted to this environment through higher catalytic rates, lower Arrhenius activation energies (Ea), and increases in the apparent Michaelis constant for the substrate pyruvate (KmPYR). Here, site directed mutagenesis was used to determine which amino acid substitutions found in A4-LDH of the notothenioid Chaenocephalus aceratus, with respect to orthologs from warm adapted teleosts, are responsible for these adaptive changes in enzyme function. KmPYR was measured in eight single- and two double-mutants, and Ea was tested in five single- and two double-mutants in the temperature range 0 - 20°C. Of the four mutants that had an effect on these parameters, two increased Ea but did not affect KmPYR (Gly224Ser, Ala310Pro), and two increased both Ea and KmPYR (Glu233Met, Gln317Val). The double mutants Glu233Met / Ala310Pro and Glu233Met / Gln317Val increased KmPYR and Ea to levels not significantly different from the A4-LDH of a warm temperate fish (Gillichthys mirabilis, habitat temperature 10 - 35°C). The four single mutants are associated with two {alpha}- helices that move during the catalytic cycle; those that affect Ea but not KmPYR are further from the active site than those that affect both parameters. These results provide evidence that: 1) cold adaptation in A4-LDH involves changes in mobility of catalytically important molecular structures; 2) these changes may alter activation energy alone, or activation energy and substrate affinity together; and 3) the extent to which these parameters are affected may depend on the location of the substitutions within the mobile {alpha} helices, perhaps due to differences in proximity to the active site.

Keywords: Activation energy; cold adaptation; notothenioids; protein stability; site-directed mutagenesis; substrate affinity.
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 J. Exp. Biol.Home page
Y. Dong and G. N. Somero
Temperature adaptation of cytosolic malate dehydrogenases of limpets (genus Lottia): differences in stability and function due to minor changes in sequence correlate with biogeographic and vertical distributions
J. Exp. Biol., January 15, 2009; 212(2): 169 - 177.
[Abstract] [Full Text] [PDF]

Home page
 J. Exp. Biol.Home page
T. Morita
Comparative sequence analysis of myosin heavy chain proteins from congeneric shallow- and deep-living rattail fish (genus Coryphaenoides)
J. Exp. Biol., May 1, 2008; 211(9): 1362 - 1367.
[Abstract] [Full Text] [PDF]

Home page
 Appl. Environ. Microbiol.Home page
D. F. Rodrigues and J. M. Tiedje
Coping with Our Cold Planet
Appl. Envir. Microbiol., March 15, 2008; 74(6): 1677 - 1686.
[Full Text] [PDF]

Home page
 Integr. Comp. Biol.Home page
F. Melzner, F. C. Mark, and H. O. Portner
Role of blood-oxygen transport in thermal tolerance of the cuttlefish, Sepia officinalis
Integr. Comp. Biol., October 1, 2007; 47(4): 645 - 655.
[Abstract] [Full Text] [PDF]

Home page
 J. Exp. Biol.Home page
P. A. Fields, E. L. Rudomin, and G. N. Somero
Temperature sensitivities of cytosolic malate dehydrogenases from native and invasive species of marine mussels (genus Mytilus): sequence-function linkages and correlations with biogeographic distribution
J. Exp. Biol., February 15, 2006; 209(4): 656 - 667.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.