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Summary: CRS2 is a peptidyl-tRNA hydrolase homolog that promotes the splicing of chloroplast group II introns in the context of heterodimeric complexes with one of two paralogous proteins CAF1 or CAF2. CRS2/CAF complexes associate in vivo with those introns whose splicing they promote. CRS2 is required for the splicing of all but one chloroplast intron in subgroup IIB. Strong crs2 mutant alleles are albino and lack chloroplast ribosomes due to defects in the splicing of various chloroplast tRNAs and ribosomal protein mRNAs.
Image: mutant leaf color depicted on a seedling color scale.
First reported: Jenkins et al. 1997.
Key Alleles
crs2-1:Mu1; Mu1 insertion is in the 5' UTR. Ivory, seedling lethal phenotype with green sectors. Stronger allele than crs2-2.
crs2-2::Mu8; Mu8 insertion is in the 5' UTR, and is flanked by a 97 bp deletion. Very pale yellow green, seedling lethal phenotype with green sectors.
Map Location
Using recombinant inbred lines mapped to 8S between isu1410a and bn19.11 (Barkan unpublished); confirmed by SNP (single nucleotide polymorphism) probe PZA01951 (NAM maps; McMullen et al. 2009); and by direct hybridization of overgo probe siAF225708_ov to the BAC physical map. (Gardiner et al. 2004)
Gene Product
Peptidyl-tRNA hydrolase homolog that is a subunit of a heterodimeric chloroplast group II intron splicing protein. (Jenkins and Barkan 2001).
Related Loci
caf1 and caf2; the protein gene product of either can serve as the second subunit in the complex with CRS2, each conferring distinct specificity on the splicing activities (Ostheimer et al. 2005, 2006).
References
Gardiner J, Schroeder S, Polacco ML, Sanchez-Villeda H, Fang Z, Morgante M, Landewe T, Fengler K, Useche F, Hanafey M, Tingey S, Chou H, Wing R, Soderlund C, Coe EH Jr (2004) Anchoring 9,371 maize expressed sequence tagged unigenes to the bacterial artificial chromosome contig map by two-dimensional overgo hybridization. Plant Physiol 134:1317-1326. PUBMED
Jenkins BD, Barkan A (2001) Recruitment of a peptidyl-tRNA hydrolase as a facilitator of group II intron splicing in chloroplasts. EMBO J 20: 872-879. PUBMED
Jenkins B, Kulhanek D, Barkan A (1997) Nuclear mutations that block group II RNA splicing in maize chloroplasts reveal several intron classes with distinct requirements for splicing factors. Plant Cell 9: 283-296. PUBMED
McMullen MD, Kresovich S, Villeda HS, Bradbury P, Li H, Sun Q, Flint-Garcia S, Thornsberry J, Acharya C, Bottoms C, Brown P, Browne C, Eller M, Guill K, Harjes C, Kroon D, Lepak N, Mitchell SE, Peterson B, Pressoir G, Romero S, Oropeza Rosas M, Salvo S, Yates H, Hanson M, Jones E, Smith S, Glaubitz JC, Goodman M, Ware D, Holland JB, Buckler ES (2009) Genetic properties of the maize nested association mapping population. Science 325:737-740. PUBMED
Ostheimer GJ, Hadjivassiliou H, Kloer DP, Barkan A, Matthews BW (2005) Structural analysis of the group II intron splicing factor CRS2 yields insights into its protein and RNA interaction surfaces. J Mol Biol 345: 51-68. PUBMED
Ostheimer GJ, Rojas M, Hadjivassiliou H, Barkan A (2006) Formation of the CRS2-CAF2 group II intron splicing complex is mediated by a 22-amino acid motif in the COOH-terminal region of CAF2. J Biol Chem 281: 4732-4738. PUBMED
Links: MGDB: crs2 NCBI:crs2 UniProt: Q9M5P4