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BBA - Gene Structure and Expression (v.1729, #3)
Identification of a CaRAV1 possessing an AP2/ERF and B3 DNA-binding domain from pepper leaves infected with Xanthomonas axonopodis pv. glycines 8ra by differential display by Soo-Yong Kim; Young-Cheol Kim; Jeong-Hee Lee; Sang-Keun Oh; Eunsook Chung; Sanghyeob Lee; Yong-Hwan Lee; Doil Choi; Jeong Mee Park (pp. 141-146).
We isolated a cDNA clone, CaRAV1, which exhibited significant similarity to those of Arabidopsis RAV proteins containing AP2/ERF and B3-like DNA-binding domains. CaRAV1 expression was rapidly and specifically induced in both host and non-host resistant responses against bacterial pathogens in the chili pepper plant. CaRAV1 also strongly increased following salicylic acid and ethephon treatments, whereas methyl-jasmonate only had mild effects. Furthermore, CaRAV1 transcript levels were also investigated in response to ABA and abiotic stress. No significant CaRAV1 expression was evident following ABA, mannitol, or cold treatments. These observations collectively provide initial evidence that the pepper RAV transcription factor homolog may function in plant defense responses.
Keywords: AP2/ERF-domain; Chili pepper; Host resistance; Hypersensitive response; Non-host resistance; RAV transcription factor
Different localization in rat brain of the novel cytosolic ketone body-utilizing enzyme, acetoacetyl-CoA synthetase, as compared to succinyl-CoA:3-oxoacid CoA-transferase by Mizuomi Ohnuki; Noriko Takahashi; Masahiro Yamasaki; Tetsuya Fukui (pp. 147-153).
In lipogenic tissue cytosol, ketone bodies are known to be activated by acetoacetyl-CoA synthetase (AACS) and incorporated into cholesterol and fatty acids. In order to investigate the physiological role of AACS in the brain, we examined the localization of AACS mRNA in rat brain by in situ hybridization using a labeled probe. High labeling was observed in the midbrain, pons/medulla, cerebral cortex, hippocampus and cerebellum, and the localization profile of AACS mRNA was different from that of succinyl-CoA:3-oxoacid CoA-transferase (SCOT), a mitochondrial ketone body-activating enzyme. In addition, the expression of AACS mRNA in the cerebellum was restricted primarily to glial cells, while in the cerebral cortex, it was restricted to neuronal cells. Streptozotocin treatment caused remarkable decreases in AACS mRNA levels in all regions where expression was observed, but changes in SCOT mRNA levels were not observed. These results suggest that the physiological role of AACS is different from that of SCOT and varies depending upon its localization in the brain.
Keywords: Abbreviations; AACS; acetoacetyl-CoA synthetase; SCOT; succinyl-CoA:3-oxoacid CoA-transferase; HMGCR; 3-hydroxy-3-methylglutaryl-CoA reductase; ACC; acetyl-CoA carboxylaseAcetoacetyl-CoA synthetase; Ketone body; Brain; Succinyl-CoA:3-oxoacid CoA-transferase; 3-Hydroxy-3-methylglutaryl-CoA reductase; In situ hybridization
cDNA cloning and regulation of two sex-hormone-repressed hamster tear lipocalins having homology with odorant/pheromone-binding proteins by Subramanya Srikantan; Vishwas Parekh; Prabir K. De www.ccmbindia.org (pp. 154-165).
A major 20-kDa protein is female-specifically expressed in exorbital lacrimal gland (LG) of hamsters and secreted in tears. Here, we identify this female-specific LG protein (FLP) as a lipocalin, having 85% protein sequence identity with male-specific submandibular salivary gland proteins (MSP) secreted in saliva and urine of male hamsters. MSP is also female-specifically expressed in LG and secreted in tears but FLP was undetectable in submandibular gland (SMG). FLP and MSP have similar sex-hormonal regulation in LG, which is different from regulation of MSP in SMG. Female-specific expression of FLP and MSP in LG is due to their incomplete repression by endogenous estrogens and gonadectomy in both sexes and lactation in females resulted in their marked induction, which was prevented by estrogen or androgen treatment. FLP and MSP show best sequence identity with odorant/pheromone-binding lipocalins (58–29%). Maximum identity (58%) is with rat odorant-binding protein (OBP) expressed in lateral nasal glands, followed by aphrodisin of hamster vaginal discharge (39%). Cognate transcript and a cross-reacting 20-kDa protein were detected in nasal glands of rat in both sexes but not in hamsters. Results suggest that two closely related lipocalin genes encode FLP and MSP, which are evolutionarily closer to rat OBP than to hamster aphrodisin and these have evolved different tissue-specificity and sex-hormonal regulation. Possible functions for FLP and MSP are suggested, considering their homology to odorant/pheromone-binding lipocalins, their presence in tears, saliva and urine as well as their sex-specific and lactation-induced expression.
Keywords: Lacrimal; Tear lipocalin; Submandibular; Odorant-binding; Pheromone-binding; Sex-specific; Sex-hormone
Genes coding for SecG and Leu2-tRNA form an operon to give an unusual RNA comprising mRNA and a tRNA precursor by Ken-ichi Nishiyama; Hajime Tokuda (pp. 166-173).
The secG gene encoding the SecG subunit of the SecYEG translocon and the leuU gene encoding Leu2-tRNA are very closely located on the Escherichia coli chromosome. A secG–leuU disruptant was not viable unless secG–leuU was induced from a plasmid, indicating that leuU is an essential gene since secG is dispensable at 37 °C. A mutant strain in which the promoter region for secG was replaced with cat revealed the same phenotype as the secG–leuU disruptant, indicating that leuU was expressed from the secG promoter. When the secG–leuU locus was placed on a high copy plasmid, an RNA comprising both mRNA for SecG and a precursor for Leu2-tRNA was detected on a Northern blot. Moreover, a secG–leuU transcript was amplified by RT-PCR using the total RNA fraction prepared from wild type E. coli cells but not from the secG–leuU and the secG promoter disruptants, indicating that secG–leuU forms an operon. Thus, the expression of Leu2-tRNA requires expression of the upstream secG gene. The gene structure of secG–leuU was conserved among Gram-negative bacteria, although the sequences separating the two genes were quite diverse. The physiological significance of this unusual gene organization is discussed.
Keywords: SecG; Leu2-tRNA; Operon; mRNA; Gene disruption
Cloning and functional characterization of NtCPK4, a new tobacco calcium-dependent protein kinase by Mei Zhang; Shuping Liang; Ying-Tang Lu (pp. 174-185).
A cDNA clone, encoding calcium (Ca2+)-dependent protein kinase (CDPK or CPK), was isolated from tobacco ( Nicotiana tabacum). The full-length cDNA of 2360 bp contains an open reading frame for NtCPK4 consisting of 572 amino acid residues. Sequence alignment indicated that NtCPK4 shared high similarities with other CPKs and some CPK-related protein kinases (CRKs). Biochemical analyses showed that NtCPK4 phosphorylated itself and calf thymus histones fraction III-S (histone III-S) in a calcium-dependent manner, and the K0.5 of calcium activation was 0.29 μM or 0.25 μM with histone III-S or syntide-2 as substrates, respectively. The Vmax and Km were 588 nmol min−1 mg−1 and 176 μg ml−1, respectively, when histone III-S was used as substrate, while they were 2415 nmol min−1 mg−1 and 58 μM, respectively, with syntide-2 as substrate. In addition, the phosphorylation of NtCPK4 occurred on threonine residue, as shown by capillary electrophoresis analyses. All of these data demonstrated that NtCPK4 was a serine/threonine protein kinase. NtCPK4 as a low copy gene was expressed in all tested organs including the root, leaf, stem, and flower of tobacco, while its expression was temporally and spatially modulated in both productive and vegetative tissues during tobacco growth and development. NtCPK4 expression was also increased in response to the treatment of gibberellin or NaCl. Our study suggested that NtCPK4 might play vital roles in plant development and responses to environmental stimuli.
Keywords: Abbreviations; CPK or CDPK; Ca; 2+; -dependent protein kinase; CRK; CPK-related kinase; CaM; calmodulin; CBK; calmodulin-binding protein kinase; CaMK; Ca; 2+; /CaM-dependent protein kinase; CCaMK; chimeric Ca; 2+; /CaM-dependent protein kinase; MCK; maize homologue of mammalian CaMK; histone III-S; calf thymus histones fraction III-S; Ni-NTA; Ni; 2+; -nitrilotriacetate; FITC; fluorescein isothiocyanateCalcium-dependent protein kinase; Phosphorylation; Gene expression; Nicotiana tabacum
Maize cystatins respond to developmental cues, cold stress and drought by Agnès Massonneau; Pascal Condamine; Jean-Pierre Wisniewski; Michel Zivy; Peter M. Rogowsky (pp. 186-199).
Comprehensive searches of maize EST data allowed us to identify 8 novel Corn Cystatin ( CC) genes in addition to the previously known genes CCI and CCII. The deduced amino acid sequences of all 10 genes contain the typical cystatin family signature. In addition, they show an extended overall similarity with cystatins from other species that belong to several different phyto-cystatin subfamilies. To gain further insight into their respective roles in the maize plant, gene-specific expression profiles were established by semi-quantitative RT-PCR. While 7 CC genes were expressed in two or more tissues varying from gene to gene, CCI was preferentially expressed in immature tassels and CC8 and CC10 in developing kernels. As shown by in situ hybridisation of maize kernels, CC8 was specifically expressed in the basal region of the endosperm and CC10 both in the starchy endosperm and the scutellum of the embryo. The remaining, not kernel-specific genes, all had distinct expression kinetics during kernel development, generally with peaks during the early stages. In addition to developmental regulation, the effect of cold stress and water starvation were tested on cystatin expression. Two genes ( CC8 and CC9) were induced by cold stress and 5 genes ( CCII, CC3, CC4, CC5 and CC9) were down-regulated in response to water starvation. Taken together our data suggest distinct functions for CC genes in the maize plant.
Keywords: Cystatin; Kernel; Maize; Stress; Zea mays
A novel PDIP1-related protein, KCTD10, that interacts with proliferating cell nuclear antigen and DNA polymerase δ by Jianlin Zhou; Kaiqun Ren; Xin Liu; Xiwen Xiong; Xiaoxiao Hu; Jian Zhang (pp. 200-203).
Rat potassium channel tetramerisation domain-containing 10 (KCTD10) gene was cloned and identified as a novel member of polymerase delta-interacting protein 1 (PDIP1) gene family. Rat KCTD10 is highly expressed in lung and moderately expressed in heart and testis. KCTD10 shares significant similarity in amino acid sequence to PDIP1 and can interact with the small subunit of DNA polymerase δ and PCNA as PDIP1 does. Like PDIP1, the expression of KCTD10 gene can be induced by TNF-α in NIH3T3 cells.
Keywords: Potassium channel tetramerisation domain-containing 10 (KCTD10); Polymerase delta-interacting protein 1 (PD1P1); TNF-α inducible protein; DNA polymerase δ; Proliferating cell nuclear antigen (PCNA)