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Abstract

The tomato LCA1 gene encodes a Ca2+-ATPase and gives rise to two major mRNA transcripts and two distinct protein products of different size in tomato roots. The basis of the transcript size difference was investigated to assess whether the mRNA transcripts encoded distinct protein products. Primer extension and S1 nuclease analysis identified two transcription initiation sites at -72 and -1392 from the start of translation. RNA gel blot analysis of poly(A)+ RNA isolated from phosphate-starved tomato roots using probes designed to domains of the 5'-untranslated region (UTR) or the full-length LCA1 cDNA identified mRNAs of 4.7 and 3.6 kb, corresponding to mRNA originating from transcription initiation sites -1392 and -72, respectively. Screening of a cDNA library derived from phosphate-starved tomato roots yielded three cDNA clones, LCA1A, LCA1B and LCA1C (3.6, 4.5 and 5.1 kb respectively). These cDNAs contain full-length LCA1 mRNA sequence derived from each transcription initiation site, with LCA1C additionally containing an intron of 0.6 kb. Sequence analysis indicated 100% identity between the three size classes of cDNA clones except for the differential 5'-UTR and the unspliced intron. Overall, the results indicate that the two major LCA1 mRNA transcripts are derived by differential transcription initiation and that two of the mRNAs may encode identical protein products, while a third mRNA may correspond to a non-functional truncated protein.

A Regulatory Cysteine Residue Mediates Reversible Inactivation of NAD+-Dependent Aldehyde Dehydrogenases to Promote Oxidative Stress Response

“…13,14 In Saccharomyces cerevisiae, there are 5 isoforms of ALDHs. 15 They are important for yeast to metabolize ethanol. [16][17][18] ALDHs are either NAD + -dependent or NADP + -dependent, generating NADH and NADPH, respectively, via their enzymatic activity.…”

“…Yeast contains 5 isoforms of aldehyde dehydrogenase, Ald2, Ald3, Ald4, Ald5 and Ald6. 15 Among them, Ald2 and Ald3 are mostly responsible for CoA generation by oxidizing 3aminopropanal into β-alanine. 18 Ald4, Ald5 and Ald6 are mostly responsible for metabolizing acetaldehyde generated through ethanol metabolism.…”