A plastid-resident basic helix–loop–helix protein, previously identified in Nicotiana tabacum and designated as NtWIN4 (N. tabacum wound-induced clone 4), has been converted from a nuclear transcription repressor into a plastid-resident regulatory factor through replacement of the DNA-binding domain with a plastid transit sequence during evolution. N. tabacum is a natural amphidiploid plant derived from Nicotiana tomentosiformis and Nicotiana sylvestris and immunoblot staining using anti-NtWIN4 antibodies identified two protein species, a 26 kDa form and a 17 kDa form, in N. sylvestris, whereas only the 17 kDa form was found in N. tabacum. The 26 kDa protein is produced when translation starts from the first AUG codon of the mRNA and is predominantly localized in the cytoplasm and nucleus, whereas the 17 kDa protein is derived from a 24 kDa precursor protein, synthesized from the second AUG codon, and localizes only to plastids. Subsequent analyses revealed that the lengths of the mRNAs vary in the two plant species. One major form lacks the first AUG, while minor populations possess variable 5′-untranslated regions prior to the first AUG codon. Translation of the two types produces the 24 kDa and 26 kDa proteins respectively. In vitro translation assays indicated that initiation frequency from the first AUG codon is higher in mRNAs from N. sylvestris than from N. tabacum. In contrast, initiation from the second AUG codon was found to be equally efficient in mRNAs from both species. These results suggest that both mRNA populations and translation efficiency changed during the amphidiploidization responsible for generation of N. tabacum. This scheme could reflect a molecular mechanism of protein evolution in plants.
Skip Nav Destination
Article navigation
May 2007
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkEditorial Board
Research Article|
April 12 2007
Functional diversification of a basic helix–loop–helix protein due to alternative transcription during generation of amphidiploidy in tobacco plants
Yutaka Kodama;
Yutaka Kodama
1Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630-0192, Japan
Search for other works by this author on:
Hiroshi Sano
Hiroshi Sano
1
1Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630-0192, Japan
1To whom correspondence should be addressed (email sano@gtc.naist.jp).
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
January 02 2007
Revision Received:
February 05 2007
Accepted:
February 08 2007
Accepted Manuscript online:
February 08 2007
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London
2007
Biochem J (2007) 403 (3): 493–499.
Article history
Received:
January 02 2007
Revision Received:
February 05 2007
Accepted:
February 08 2007
Accepted Manuscript online:
February 08 2007
Connected Content
A correction has been published:
Evolutionary tinkering: birth of a novel chloroplast protein
Citation
Yutaka Kodama, Hiroshi Sano; Functional diversification of a basic helix–loop–helix protein due to alternative transcription during generation of amphidiploidy in tobacco plants. Biochem J 1 May 2007; 403 (3): 493–499. doi: https://doi.org/10.1042/BJ20070011
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.