Affiliation:
1. Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, and Core Research for Evolutional Science and Technology Program of Japan Science and Technology Corporation (CREST-JST), Kawaguchi, Saitama 332-0012, Japan
Abstract
ABSTRACT
We had previously isolated a facultatively anaerobic hyperthermophilic archaeon,
Pyrobaculum calidifontis
strain VA1. Here, we found that strain VA1, when grown under aerobic conditions, harbors high catalase activity. The catalase was purified 91-fold from crude extracts and displayed a specific activity of 23,500 U/mg at 70°C. The enzyme exhibited a
K
m
value of 170 mM toward H
2
O
2
and a
k
cat
value of 2.9 × 10
4
s
−1
·subunit
−1
at 25°C. Gel filtration chromatography indicated that the enzyme was a homotetramer with a subunit molecular mass of 33,450 Da. The purified catalase did not display the Soret band, which is an absorption band particular to heme enzymes. In contrast to typical heme catalases, the catalase was not strongly inhibited by sodium azide. Furthermore, with plasma emission spectroscopy, we found that the catalase did not contain iron but instead contained manganese. Our biochemical results indicated that the purified catalase was not a heme catalase but a manganese (nonheme) catalase, the first example in archaea. Intracellular catalase activity decreased when cells were grown anaerobically, while under aerobic conditions, an increase in activity was observed with the removal of thiosulfate from the medium, or addition of manganese. Based on the N-terminal amino acid sequence of the purified protein, we cloned and sequenced the catalase gene (
kat
Pc
). The deduced amino acid sequence showed similarity with that of the manganese catalase from a thermophilic bacterium,
Thermus
sp. YS 8-13. Interestingly, in the complete archaeal genome sequences, no open reading frame has been assigned as a manganese catalase gene. Moreover, a homology search with the sequence of
kat
Pc
revealed that no orthologue genes were present on the archaeal genomes, including those from the “aerobic” (hyper)thermophilic archaea
Aeropyrum pernix
,
Sulfolobus solfataricus
, and
Sulfolobus tokodaii
. Therefore, Kat
Pc
can be considered a rare example of a manganese catalase from archaea.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Reference46 articles.
1. Characterization of a manganese-containing catalase from the obligate thermophile Thermoleophilum album
2. Amo T. M. L. F. Paje A. Inagaki S. Ezaki H. Atomi and T. Imanaka. Pyrobaculum calidifontis sp. nov. a novel hyperthermophilic archaeon which grows under atmospheric air. Archaea in press. [Online.] http://www.archaea.ws/
.
3. Antonyuk, S. V., V. R. Melik-Adamyan, A. N. Popov, V. S. Lamzin, P. D. Hempstead, P. M. Harrison, P. J. Artymyuk, and V. V. Barynin. 2000. Three-dimensional structure of the enzyme dimanganese catalase from Thermus thermophilus at 1 Å resolution. Crystallography Rep.45:105-116.
4. Methanogens: reevaluation of a unique biological group
5. Barynin, V. V., and A. I. Grebenko. 1986. T-catalase is nonheme catalase of extremely thermophilic bacterium Thermus thermophilus HB-8. Dolk. Akad. Nauk. USSR286:461-464. (In Russian.)
Cited by
80 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献