Os08g0424500
Os08g0424500 is reported as Badh2, encoding betaine aldehyde dehydrogenase (BADH2) .
Contents
Annotated Information
Function
BADH2, encoding betaine aldehyde dehydrogenase (BADH2) inhibits the synthesis of 2-acetyl-1-pyrroline (2AP), a potent flavor component in rice fragrance.In rice the nitrogen in the pyrroline ring of proline becomes the nitrogen in the pyrroline ring of 2AP while the carboxyl group of proline is removed and replaced with an acetyl group from another source found that in L. hilgardii the acetyl group of 2AP can be derived from fructose when either ethanol or acetaldehyde are supplied in excess. They further suggested D1pyrroline, a product of proline catabolism via putrescine oxidation, is the immediate precursor of the pyrroline ring of 2AP and the acetyl group was most likely formed from reaction with acetyl-CoA or acetaldehyde in either a chemical or enzymatic reaction. Additionally, detailed precursor studies have revealed that the formation of 2AP in Bacillus cerus proceeds via acetylation of D1pyrroline.
The intact BADH2 protein encoded by the complete Badh2 gene sequence was shown to influence this critical switch, possibly due to its strong AB-ald dehydrogenase activity. From its activity in vitro, we conclude that, in nonfragrant rice, the BADH2 enzyme converts AB-ald into GABA, inhibiting 2AP biosynthesis. In fragrant rice lacking intact BADH2, failure to convert AB-ald into GABA due to the absence of BADH2 enzymatic activity results in AB-ald accumulation, which activates 2AP biosynthesis. Interestingly, the low level of BADH2 detected in some transgenic lines overexpressing Badh2 might not completely inhibit the consumption of AB-ald, resulting in a small quantity of 2AP.
Protein Structure
BADH2 could be divided into three domains: a NAD binding domain (residues 9 to 124 and 152 to 262), an oligomerization domain (residues 129 to 151 and 480 to 486), and a substrate binding domain (residues 263 to 464).
Expression
In the nonfragrant rice cv Nanjing11, Badh2 transcripts were detected in all tissues tested except for the roots. The Badh2 transcript was more abundant in the initial fully expanded leaf than in other tissues (Figure 3). Interestingly, a similar transcription pattern with a lower transcription level was observed for the badh2-E7 allele in the fragrant rice cv Wuxiangjing (Figure 3). This indicates that sequence alterations specific to the badh2-E7 allele significantly reduce its transcription levels but cause only a slight change in its transcription pattern.
The major transcription start point was downstream of the predicted Badh2 start codon, resulting in very few complete Badh2 transcripts but abundant partial Badh2 transcripts. Transcription of the Badh2 gene was severely suppressed in fragrant rice varieties.
BADH2 is highly expressed during cell division. BADH2 is mainly in the cytoplasm and none of the BADH2 is observed to be localized in the nucleus.
Evolution
The production of two different subunits in the same subcellular compartment allows for the possible formation of heterodimers of the two subunits. The presence of such heterodimers might lead to an altered substrate specificity of BAD in rice. The presence of two BAD homologues has been widely reported in many grasses, and the BAD2 protein in rice appears to be closely related to the BAD2 protein from wheat, barley, sorghum, maize and the turfgrass Zoysia tenuifolia (Figure 6). Analysis of the sequences in genes from other species (Figure 6) shows that BAD2s from different species are more closely related than different BADs from the same species, suggesting a distinct and important role for each of the two BADs. However, only the BAD2 protein in Z. tenuifolia has a similar PTS1 at its C-terminus.
Labs working on this gene
- National Maize Improvement Center of China, China Agricultural University, Beijing 100193, People’s Republic of China
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, People’s Republic of China
- College of Biological Sciences, China Agricultural University, Beijing 100193, People’s Republic of China
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
- Beijing Key Laboratory of Crop Genetic Improvement, Beijing 100193, People’s Republic of China
- Centre for Plant Conservation Genetics, Southern CrossUniversity, Military Road, Lismore, NSW 2480, Australia
- L. M. T. Bradbury , S. A. Gillies ,R. J. Henry Grain Foods CRC, Southern Cross University, Lismore, NSW 2480, Australia
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Faculty of Medical Technology, Huachiew Chalermprakiet University, Samut Prakran 10540, Thailand
- Rice Gene Discovery Unit, Kasetsart University, Kamphangsaen Campus, Nakhon Pathom 73140, Thailand
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Saihua Chen,Yi Yang, Weiwei Shi, Qing Ji, Fei He,Ziding Zhang, Zhukuan Cheng, Xiangnong Liu, Mingliang Xu, Badh2, Encoding Betaine Aldehyde Dehydrogenase, Inhibits the Biosynthesis of 2-Acetyl-1-Pyrroline, a Major Component in Rice Fragrance, The Plant Cell, July 2008, Vol. 20: 1850–1861.
- ↑ Cite error: Invalid
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3. Louis M. T. Bradbury ,Susan A. Gillies Donald J. Brushett, Daniel L. E. Waters Robert J. Henry, Encoding Betaine Aldehyde Dehydrogenase, Inhibits the Biosynthesis of 2-Acetyl-1-Pyrroline, a Major Component in Rice Fragrance,Plant Mol Biol (2008) 68:439–449.
4. Ratree Wongpanya , Nonlawat Boonyalai , Napaporn Thammachuchourat, Natharinee Horata , Siwaret Arikit, Khin Myo Myint, Biochemical and Enzymatic Study of Rice BADH Wild-Type and Mutants: An Insight into Fragrance in Rice, Protein J (2011) 30:529–538