HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 281, Issue 18, 12610-12617, May 5, 2006

This Article Full Text Full Text (PDF) All Versions of this Article: 281/18/12610    most recent M600061200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tosha, T. Articles by Kitagawa, T. Search for Related Content PubMed PubMed Citation Articles by Tosha, T. Articles by Kitagawa, T. Social Bookmarking                      What's this?

On the Relationship of Coral Allene Oxide Synthase to Catalase

A SINGLE ACTIVE SITE MUTATION THAT INDUCES CATALASE ACTIVITY IN CORAL ALLENE OXIDE SYNTHASE^*

Takehiko Tosha¹, Takeshi Uchida², Alan R. Brash, and Teizo Kitagawa³

From the Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki 444-8787, Japan and the Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6602

A heme domain of coral allene oxide synthase (cAOS) catalyzes the formation of allene oxide from fatty acid hydroperoxide. Although cAOS has a similar heme active site to that of catalase, cAOS is completely lacking in catalase activity. A close look at the hydrogen-bonding possibilities around the distal His in cAOS suggested that the imidazole ring is rotated by 180° relative to that of catalase because of the hydrogen bond between Thr-66 and the distal His-67. This could contribute to the functional differences between cAOS and catalase, and to examine this possibility, we mutated Thr-66 in cAOS to Val, the corresponding residue in catalase. In contrast to the complete absence of catalase activity in wild type (WT) cAOS, T66V had a modest catalase activity. On the other hand, the mutation suppressed the native enzymatic activity of the formation of allene oxide to 14% of that of WT cAOS. In the resonance Raman spectrum, whereas WT cAOS has only a 6-coordinate/high spin heme, T66V has a 5-coordinate/high spin heme as a minor species. Because catalase adopts a 5-coordinate/high spin structure, probably the 5-coordinate/high spin portion of T66V showed the catalase activity. Furthermore, in accord with the fact that the CN affinity of catalase is higher than that of WT cAOS, the CN affinity of T66V was 8-fold higher than that of WT cAOS, indicating that the mutation could mimic the heme active site in catalase. We, therefore, propose that the hydrogen bond between Thr-66 and distal His-67 could modulate the orientation of distal His, thereby regulating the enzymatic activity in cAOS.

Received for publication, January 4, 2006 , and in revised form, February 28, 2006.

^* This work was supported by a Grant-in-aid for Specifically Promoted Research (14001004, to T. K.) from the Ministry of Education, Culture, Sports, Science and Technology, Japan, and by National Institutes of Health Grant GM-53638 and Pilot Project Grant P30 ES000267 (to A. R. B.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ Supported by a research fellowship from the Japan Society for the Promotion of Science for young scientists.

² Present address: Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.

³ To whom correspondence should be addressed. Tel.: 81-564-59-5225; Fax: 81-564-59-5229; E-mail: teizo{at}ims.ac.jp.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				S. Ichimura, T. Uchida, S. Taniguchi, S. Hira, T. Tosha, I. Morishima, T. Kitagawa, and K. Ishimori Unique Peroxidase Reaction Mechanism in Prostaglandin Endoperoxide H Synthase-2: COMPOUND I IN PROSTAGLANDIN ENDOPEROXIDE H SYNTHASE-2 CAN BE FORMED WITHOUT ASSISTANCE BY DISTAL GLUTAMINE RESIDUE J. Biol. Chem., June 1, 2007; 282(22): 16681 - 16690. [Abstract] [Full Text] [PDF]