Document Detail

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.
MedLine Citation:
PMID:  19112135     Owner:  NLM     Status:  MEDLINE    
We characterized functional and structural properties of cytoplasmic malate dehydrogenases (cMDHs) from six limpets of the genus Lottia that have different vertical and latitudinal distributions. Particular attention was given to the cryptic species pair Lottia digitalis (northern occurring) and L. austrodigitalis (southern occurring) because of recent contraction in the southern range of L. digitalis and a northward range extension of L. austrodigitalis. As an index of adaptation of function, we measured the effects of temperature on the apparent Michaelis-Menten constant (K(m)) of the cofactor NADH (K(m)(NADH)). K(m)(NADH) values of cMDHs from the mid- to high-intertidal, low-latitude species L. scabra and L. gigantea were less sensitive to high temperature than those of cMDHs from the low- and mid-intertidal, high-latitude species L. scutum and L. pelta. cMDH of L. digitalis was more sensitive to high temperatures than the cMDH ortholog of L. austrodigitalis. Thermal stability (rate of loss of activity at 42.5 degrees C) showed a similar pattern of interspecific variation. Comparison of the deduced amino acid sequences showed that interspecific differences ranged from one to as many as 17 residues. Differences in K(m)(NADH) and thermal stability between orthologs of L. digitalis and L. austrodigitalis result from a single amino acid substitution. At position 291, the glycine residue in cMDH of L. digitalis is replaced by a serine in cMDH of L. austrodigitalis, a change that favors additional hydrogen bonding and reduced conformational entropy. This difference between closely related congeners demonstrates the role of minor alterations in protein sequence in temperature adaptation and suggests that such variation is important in governing shifts in biogeographic range in response to climate change.
Yunwei Dong; George N Somero
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  212     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2009 Jan 
Date Detail:
Created Date:  2008-12-29     Completed Date:  2009-03-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  169-77     Citation Subset:  IM    
Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA 93950, USA.
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MeSH Terms
Adaptation, Biological
Cytosol / enzymology
DNA, Complementary / genetics
Enzyme Stability
Gastropoda / enzymology*,  physiology
Malate Dehydrogenase / chemistry,  genetics*,  metabolism*
Models, Molecular
NAD / metabolism
Protein Conformation
Protein Denaturation
Sequence Homology, Amino Acid
Reg. No./Substance:
0/DNA, Complementary; 53-84-9/NAD; EC Dehydrogenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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