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In Vivo Photomodification of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Holoenzyme by Ultraviolet-B Radiation (Formation of a 66-Kilodalton Variant of the Large Subunit).

Abstract：

:Increased levels of solar ultraviolet (290-320 nm) (UV-B) radiation could have profound effects on plant proteins because the aromatic amino acids in proteins absorb strongly in this spectral region. We have investigated the effects of UV-B radiation on plant proteins and have observed a novel 66-kD protein. This product was formed in vivo when Brassica napus L. plants grown for 21 d in 65 [mu]mol m-2 s-1 photosynthetically active radiation were subsequently exposed to 65 [mu]mol m-2 s-1 photosynthetically active radiation plus UV-B radiation (1.5 [mu]mol m-2 s-1). The protein appeared after 4 h of UV-B irradiation and accumulated during the next 16 h in UV-B. The 66-kD protein cross-reacted with an antiserum against the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) holoenzyme. Analysis of soluble leaf proteins revealed that the 66-kD product had a number of isoforms corresponding closely to those of the large subunit of Rubisco (LSU). Partial proteolytic digests of the LSU and the 66-kD protein resulted in an equivalent pattern of protein fragments, leading to the conclusion that the 66-kD protein was a photomodified form of the LSU. A similar high molecular mass variant of Rubisco was observed in soluble protein extracts from leaves of tomato (Lycopersicon esculentum), tobacco (Nicotiana tabacum), and pea (Pisum sativum L.) plants treated in vivo with UV-B, suggesting that it might be a common product, at least among C3 plants. It is interesting that the 66-kD product appears to be generated after incorporation of the LSU into holoenzyme complexes. This conclusion was drawn from two lines of evidence. First, the LSU variant co-purified with holoenzyme complexes isolated by nondenaturing polyacrylamide gel electrophoresis. Second, a UV-B-specific 66-kD protein did not accumulate in a tobacco mutant that synthesizes the Rubisco subunits but does not assemble them into normal holoenzyme complexes.

journal_name

Plant Physiol

journal_title

Plant physiology

authors

Wilson MI,Ghosh S,Gerhardt KE,Holland N,Babu TS,Edelman M,Dumbroff EB,Greenberg BM

doi

10.1104/pp.109.1.221

subject

Has Abstract

pub_date

1995-09-01 00:00:00

pages

221-229

issue

eissn

0032-0889

issn

1532-2548

pii

109/1/221

journal_volume

109

pub_type

杂志文章

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In Vivo Photomodification of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Holoenzyme by Ultraviolet-B Radiation (Formation of a 66-Kilodalton Variant of the Large Subunit).