Characterization, chromosomal mapping, and expression of different ubiquitin fusion protein genes in tissues from control and heat-shocked maize seedlings

Abstract

Organisms possess at least two multigene families of ubiquitins: the polyubiquitins, with few to several repeat units, which encode a ubiquitin monomer, and the ubiquitin fusion (or extension) protein genes, which encode a single ubiquitin monomer and a specific protein. This report provides details about two ubiquitin fusion protein genes in maize referred to as MubG7 (uwo 1) and MubG10 (uwo 2). Each has one nearly identical ubiquitin coding unit fused without an intervening nucleotide to an unrelated, 237-nucleotide sequence that encodes for a 79 amino acid protein. The derived amino acid sequences of the two fusion proteins show that they differ by five amino acids (substitution by either a serine or threonine). MubG7 maps to chromosome 8L162 and MubG10 maps to chromosome 1L131. Analyses of the role(s) of these genes in response to heat shock (1 h at 42.5 degrees C) reveal that the level of these fusion protein mRNAs in the radicles or plumules from 2-day-old seedlings does not change; however, heat shock does cause a marked reduction in the accumulation of these same gene-specific mRNAs in the radicles and plumules of 5-day-old seedlings. These data confirm the suggestion from our earlier work that there is precise modulation, in a gene-specific manner, of the response to developmental as well as environmental signals.

Genome‐wide analysis ofGlycine sojaubiquitin (UBQ) genes and functional analysis ofGsUBQ10in response to alkaline stress

“…). Previous studies have identified some ubiquitin extension protein genes, which encode either one of two different ribosomal subunits in the C‐terminus of ubiquitin domain (Liu et al , Shaheen et al ). In this study, four G. soja ubiquitin genes and four Arabidopsis ubiquitin extension protein genes were clustered in clade C (Fig.…”

“…Previous studies reported that these three groups of genes play an important role in response to abiotic stresses. For example, the ubiquitin‐like gene HUB1 confers drought tolerance in perennial ryegrass (Patel et al ) and the ubiquitin extension genes play an important role in response to heat‐shock (Liu et al , Park et al ). However, most studies focus on the ubiquitin‐proteasome system, which has been widely reported to have multiple functional roles in regulating plant stress responses (Hwang et al , Sharma et al ).…”

Plant Abiotic Stress

“…In Arabidopsis UBQ14 levels increased in parallel with the induction of HSP70, while UBQ11 decreased (Sun & Callis, 1997). Specific ubiquitin alleles were also shown to be upregulated in specific organs after heat stress in maize (Liu et al, 1996), and a ubiquitin-conjugating enzyme has been shown to be upregulated by heat shock in tomato plants (Feussner et al, 1997). Similarly, ubiquitin pathway genes showed increased transcript levels in heat-stressed tobacco (Rizhsky et al, 2002).…”