Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nodulation by the Rhizobium strain IC3342 causes a leaf curl syndrome in certain tropical legumes such as pigeon pea (Cajanus cajan) (N.M. Upadhyaya, J.V.D.K. Kumar Rao, D.S. Letham, and P.J. Dart, Physiological and Molecular Plant Pathology 39:357-373, 1991). Transposon (Tn5) mutagenesis of this leaf curl-inducing (Curl+) Rhizobium strain yielded two Curl- Fix- and three Curl- Fix+ mutants. Plasmid visualization and subsequent Southern blot hybridization analyses with Tn5, nif and nod gene probes showed that the Tn5 element had inserted into the symbiotic (Sym) plasmid in three of the mutants. Restriction endonuclease analyses indicated that none of the Tn5 insertions were closely linked. Tn5-containing EcoRI fragments were cloned from each mutant and used as probes to isolate the corresponding wild-type DNA fragments from a cosmid (pLAFR3) genomic library. Fix+ and/or Curl+ phenotypes were restored in each mutant by the introduction of cosmids containing the corresponding wild-type DNA. A closely related but Curl- Rhizobium strain ANU240 was shown, by Southern hybridization, to contain conserved DNA sequences of all but one of the identified genetic regions of the Curl+ Rhizobium strain IC3342. Cosmids containing the genetic region unique to the strain IC3342, designated lcr1, conferred a Curl+ phenotype on the strain ANU240. DNA sequence analysis of the cloned lcr1 region revealed five open reading frames (ORFs). The ORF2 showed homology with the Escherichia coli regulatory gene ompR, and ORF4 showed homology with E. coli and Rhizobium meliloti regulatory genes fnr and fixK, respectively.
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PMID:Isolation and characterization of Rhizobium (IC3342) genes that determine leaf curl induction in pigeon pea. 131 72

The hsd locus (host specificity of DNA) was identified in the Neisseria gonorrhoeae genome. The DNA fragment encoding this locus produced an active restriction and modification (R/M) system when cloned into Escherichia coli. This R/M system was designated NgoAV. The cloned genomic fragment (7800 bp) has the potential to encode seven open reading frames (ORFs). Several of these ORFs had significant homology with other proteins found in the databases: ORF1, the hsdM, a methylase subunit (HsdM); ORF2, a homologue of dinD; ORF3, a homologue of hsdS; ORF4, a homologue of hsdS; and ORF5, an endonuclease subunit hsdR. The endonuclease and methylase subunits possessed strongest protein sequence homology to the EcoR124II R/M system, indicating that NgoAV belongs to the type IC R/M family. Deletion analysis showed that only ORF3 imparted the sequence specificity of the RM.NgoAV system, which recognizes an interrupted palindrome sequence (GCAN(8-)TGC). The genetic structure of ORF3 (208 amino acids) is almost identical to the structure of the 5' truncated hsdS genes of EcoDXXI or EcoR124II R/M systems obtained by in vitro manipulation. Genomic sequence analysis allowed us to identify hsd loci with a very high homology to RM.NgoAV in two strains of Neisseria meningitidis. However, significant differences in the organization and structure of the hsdS genes in both these systems suggests that, if functional, they would possess recognition sites that differ from the gonococcus and from themselves.
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PMID:Analysis of type I restriction modification systems in the Neisseriaceae: genetic organization and properties of the gene products. 1155 98

The nucleotide sequences of eight plasmids isolated from seven Streptococcus thermophilus strains have been determined. Plasmids pSt04, pER1-1, and pJ34 are related and replicate via a rolling circle mechanism. Plasmid pJ34 encodes for a replication initiation protein (RepA) and a small polypeptide with unknown function. Plasmids pSt04 and pER1-1 carry in addition to repA genes coding for small heat shock proteins (sHsp). Expression of these proteins is induced at elevated temperatures or low pH and increases the thermo- and acid resistance. Plasmids pER1-2 and pSt22-2 show identical sequences with five putative open reading frames (ORFs). The gene products of ORF1 and ORF4 reveal some similarities to transposon encoded proteins of Bacillus subtilis and Tn916. ORF1 of plasmid pSt106 encodes a protein similar to resolvases of different Gram-positive bacteria. Integrity of ORF2 and 3, encoding a putative DNA primase and a replication protein, is essential for replication. ORF1 to 3 of plasmid pSt08, which are organized in a tricistronic operon, encode a RepA protein, an adenosine-specific methyltransferase, and a type II restriction endonuclease. Another type II restriction-modification (R/M) system is encoded on plasmid pSt0 which is highly similar to those encoded on lactococcal plasmid pHW393 and B. subtilis plasmid pXH13. Plasmid-free derivatives of strains St0 and St08 show increased phage sensitivity, indicating that in the wild-type strains the R/M systems are functionally expressed. Recombinant plasmids based on the replicons of plasmids pSt04, pJ34, pSt106, pSt08, and pSt0, are able to replicate in Lactococcus lactis and B. subtilis, respectively, whereas constructs carrying pER1-2 only replicate in S. thermophilus.
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PMID:Sequence analysis and characterization of plasmids from Streptococcus thermophilus. 1282 58