| 11 matches found in 10 documents. Search time: 0.069 seconds. |
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| Title: Flexibility in the inducer binding region is crucial for allostery in the Escherichia coli lactose repressor .
| | Author: Xu J Matthews KS | | Journal: Biochemistry Citation: V : 48 P : 4988-98 Year: 2009 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub19368358 Accession (PMID): 19368358 | | Abstract: Lactose repressor protein ( LacI ) utilizes an allosteric mechanism to regulate transcription in Escherichia coli , and the transition between inducer and operator-bound states has been simulated by targeted molecular dynamics ( TMD ) .
The side chains of amino acids 149 and 193 interact and were predicted by TMD simulation to play a critical role in the early stages of the LacI conformational change .
D149 contacts IPTG directly , and variations at this site provide the opportunity to dissect its role in inducer binding and signal transduction .
Single mutants at D149 or S193 exhibit a minimal change in operator binding , and alterations in inducer binding parallel changes in operator release , indicating normal allosteric response .
The observation that the double mutant D149A/S193A exhibits wild-type properties excludes the requirement for inter-residue hydrogen bond formation in the allosteric response .
The double mutant D149C/S193C purified from cell extracts shows decreased sensitivity to inducer binding while retaining wild-type binding affinities and kinetic constants for both operator and inducer .
By manipulating cysteine oxidation , we show that the more reduced state of D149C/S193C responds to inducer more like the wild-type protein , whereas the more oxidized state displays diminished inducer sensitivity .
These features of D149C/S193C indicate that the novel disulfide bond formed in this mutant impedes the allosteric transition , consistent with the role of this region predicted by TMD simulation .
Together , these results establish the requirement for flexibility in the spatial relationship between D149 and S193 rather than a specific D149-S193 interaction in the LacI allosteric response to inducer .
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[ Sen. 4, subscore: 1.00 ]: Single mutants at D149 or S193 exhibit a minimal change in operator binding , and alterations in inducer binding parallel changes in operator release , indicating normal allosteric response .
[ Sen. 9, subscore: 1.00 ]: Together , these results establish the requirement for flexibility in the spatial relationship between D149 and S193 rather than a specific D149-S193 interaction in the LacI allosteric response to inducer .
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| Title: Truncated and dispersed rpl2 and rps19 pseudogenes are co-transcribed with neighbouring downstream genes in wheat mitochondria .
| | Author: Subramanian S Fallahi M Bonen L | | Journal: Curr . Genet . Citation: V : 39 ( 4 ) P : 264-72 Year: 2001 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub11453256 Accession (PMID): 11453256 | | Abstract: The wheat mitochondrial genome contains only partial coding sequences for the L2 and S19 ribosomal proteins , unlike in rice or liverwort mitochondria , where these genes are functional and have a bacterial-type linkage .
A single-copy stretch corresponding to the extreme 3 terminus of the wheat rpl2 gene is co-transcribed with the trans-splicing nad1 exon 4 ; and , at another unique location , the rps19 segment lacking the 5 coding region is co-transcribed with the downstream nad4L gene .
In both cases , the 5 termini of these transcripts map to promoter consensus motifs acquired through genomic reorganization , enabling continued expression of essential downstream genes .
In both wheat and rice , the rpl2 and rps19 genomic regions differ in their RNA profiles between germinating embryos and seedlings .
The absence of intact rpl2 and rps19 genes in wheat mitochondria is consistent with their inactivation through DNA rearrangement/deletion after the successful transfer of functional copies to the nucleus . | Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: The wheat mitochondrial genome contains only partial coding sequences for the L2 and S19 ribosomal proteins , unlike in rice or liverwort mitochondria , where these genes are functional and have a bacterial-type linkage .
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| Title: Fate of mitochondrially located S19 ribosomal protein genes after transfer of a functional copy to the nucleus in cereals .
| | Author: Fallahi M Crosthwait J Calixte S Bonen L | | Journal: Mol . Genet . Genomics Citation: V : 273 ( 1 ) P : 76-83 Year: 2005 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub15711972 Accession (PMID): 15711972 | | Abstract: Mitochondrial genes for ribosomal proteins undergo relatively frequent transfer to the nucleus during plant evolution , and when migration is successful the mitochondrial copy becomes redundant and can be lost We have examined the status of the mitochondrial rps19 gene for ribosomal protein S19 in closely related cereals .
In oat , the mitochondrial rps19 reading frame is blocked by a premature termination codon and lacks abundant transcripts , whereas in the mitochondria of wheat and rye rps19 is a 5-truncated pseudogene which is co-transcribed with the downstream nad4L gene .
In barley and maize , rps19 sequences are completely absent from the mitochondrion .
All five of these cereals differ from rice , in which an intact , transcriptionally active mitochondrial rps19 gene is found , and this is preceded by rpl2 in an organization reminiscent of that seen in bacteria .
Based on EST sequence data for maize , barley and wheat , it can be inferred that a functional rps19 gene was transferred to the nucleus prior to the divergence of the maize and rice lineages ( approximately 50 million years ago ) , and the present-day nuclear copies encode an N-terminal sequence related to the mitochondrial targeting signal of Hsp70 ( heat shock protein ) in cereals .
Subsequent evolutionary events have included independent losses of the mitochondrial copies in the barley and maize lineages .
In the rice lineage , on the other hand , the nuclear copy was lost This is reflected in the persistence of the mitochondrial rps19 after a period during which rps19 genes coexisted in both compartments .
These observations illustrate the dynamic nature of the location and structure of genes for mitochondrial ribosomal proteins in flowering plants .
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[ Sen. 1, subscore: 1.00 ]: Mitochondrial genes for ribosomal proteins undergo relatively frequent transfer to the nucleus during plant evolution , and when migration is successful the mitochondrial copy becomes redundant and can be lost We have examined the status of the mitochondrial rps19 gene for ribosomal protein S19 in closely related cereals .
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| Title: Molecular cloning and characterization of a novel SNAP25-type protein gene OsSNAP32 in rice ( Oryza sativa L ) .
| | Author: Bao YM Wang JF Huang J Zhang HS | | Journal: Mol Biol Rep Citation: V : 35 P : 145-52 Year: 2008 Type: In-Process | | Literature: oryza Field: abstract Doc ID: pub17380428 Accession (PMID): 17380428 | | Abstract: The SNAP25-type proteins belong to the superfamily of the SNAREs ( soluble N-ethylmaleimide-sensitive factor attachment protein receptors ) , and function as important components of the vesical trafficking machinery in eukaryotic cells .
In this paper , we report the cloning and expression characterization of OsSNAP32 gene , and the subcellular localization of its encoded protein .
The OsSNAP32 gene contains five exons and four introns , and is located between RFLP markers C12276S and S1917 on chromosome 2 in rice .
The OsSNAP32 has a molecular weight of 31 . 3 kD , comprises 283 amino acid residues , and contains Qb-SNARE and Qc-SNARE domains in the N and C-terminal , respectively .
Multiple sequence alignment of the SNARE domains indicates that OsSNAP32 protein is homologous to HvSNAP34 and HvSNAP28 ( 63% and 55% of amino acid identity respectively ) from barley .
The transient expression method in onion epidermal cells , revealed that OsSNAP32 is located in the plasma membrane , like other SNAP25-type proteins .
Semi-quantitative RT-PCR assay showed that the OsSNAP32 is highly expressed in leaves and culms , and low in roots of rice , while hardly detected in immature spikes and flowering spikes .
The expression of OsSNAP32 was significantly activated in rice seedlings treated with H2O2 , PEG6000 , and low temperature or after inoculation with rice blast ( Magnaporthe grisea strain Hoku 1 ) .
The results suggest that this gene belongs to a novel member of this gene family encoding SNAP25-type proteins , involved in the rice responses to biotic and abiotic stresses .
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[ Sen. 3, subscore: 1.00 ]: The OsSNAP32 gene contains five exons and four introns , and is located between RFLP markers C12276S and S1917 on chromosome 2 in rice .
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| Title: STS markers for the wheat yellow rust resistance gene Yr5 suggest a NBS-LRR-type resistance gene cluster .
| | Author: Smith PH Hadfield J Hart NJ Koebner RM Boyd LA | | Journal: Genome Citation: V : 50 P : 259-65 Year: 2007 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub17502899 Accession (PMID): 17502899 | | Abstract: Two sequence-tagged site ( STS ) markers for the wheat yellow rust resistance ( R ) gene Yr5 have been derived through the identification and characterization of linked amplified fragment length polymorphisms ( AFLPs ) .
The sequences of the 2 AFLP markers partially overlap with one another , but belong to discrete loci : S19M93-140 completely cosegregates with Yr5 , whereas S23M41-310 maps at a distance of 0 . 7 cM .
The DNA sequence of S23M41-310 shows significant homology with the 3 end of nucleotide-binding site ( NBS ) - leucine-rich repeat ( LRR ) - type R-genes , in particular with orthologues of the rice bacterial blight R-gene Xa-I The distinct genetic location of the 2 AFLP loci suggests that Yr5 falls within an R-gene cluster .
Because neither sequence forms part of a detectable transcription product , we propose that the Yr5 R-gene cluster includes R-gene analogues and pseudogenes .
A Yr5 flanking simple sequence repeat ( SSR ) marker has also been identified , which allows Yr5 to be effectively incorporated , along with other R-genes for yellow rust , into elite wheat genetic backgrounds , through marker-assisted selection .
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[ Sen. 2, subscore: 1.00 ]: The sequences of the 2 AFLP markers partially overlap with one another , but belong to discrete loci : S19M93-140 completely cosegregates with Yr5 , whereas S23M41-310 maps at a distance of 0 . 7 cM .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
