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Structural and biochemical characterization of novel carbonic anhydrases from Phaeodactylum tricornutum
Author(s) -
Jin Shengyang,
Vullo Daniela,
Bua Silvia,
Nocentini Alessio,
Supuran Claudiu T.,
Gao Yong-gui
Publication year - 2020
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.374
H-Index - 138
ISSN - 2059-7983
DOI - 10.1107/s2059798320007202
Subject(s) - phaeodactylum tricornutum , bicarbonate , biochemistry , carbonic anhydrase , chemistry , protein family , photosynthesis , mutant , biology , diatom , enzyme , botany , gene , organic chemistry
Carbonic anhydrases (CAs) are a well characterized family of metalloenzymes that are highly efficient in facilitating the interconversion between carbon dioxide and bicarbonate. Recently, CA activity has been associated with the LCIB (limiting CO 2 ‐inducible protein B) protein family, which has been an interesting target in aquatic photosynthetic microorganisms. To gain further insight into the catalytic mechanism of this new group of CAs, the X‐ray structure of a highly active LCIB homolog (PtLCIB3) from the diatom Phaeodactylum tricornutum was determined. The CA activities of PtLCIB3, its paralog PtLCIB4 and a variety of their mutants were also measured. It was discovered that PtLCIB3 has a classic β‐CA fold and its overall structure is highly similar to that of its homolog PtLCIB4. Subtle structural alterations between PtLCIB3 and PtLCIB4 indicate that an alternative proton‐shuttle cavity could perhaps be one reason for their remarkable difference in CA activity. A potential alternative proton‐shuttle route in the LCIB protein family is suggested based on these results.