Home About us Contact
|
Home About us Contact | ||
|
|
||
KH Domain (kh + domain)
Selected AbstractsMolecular and functional characterization of a novel splice variant of ANKHD1 that lacks the KH domain and its role in cell survival and apoptosiscFEBS JOURNAL, Issue 16 2005Melissa C. Miles Multiple ankyrin repeat motif-containing proteins play an important role in protein,protein interactions. ANKHD1 proteins are known to possess multiple ankyrin repeat domains and a single KH domain with no known function. Using yeast two-hybrid system analysis, we identified a novel splice variant of ANKHD1. This splice variant of ANKHD1, which we designated as HIV-1 Vpr-binding ankyrin repeat protein (VBARP), does not contain the signature KH domain, and codes for only a single ankyrin repeat motif. We characterized VBARP by molecular and functional analysis, revealing that VBARP is ubiquitously expressed in different tissues as well as cell lines of different lineage. In addition, blast searches indicated that orthologs and homologs to VBARP exist in different phyla, suggesting that VBARP might be evolutionarily conserved, and thus may be involved in basic cellular function(s). Furthermore, biochemical analysis revealed the presence of two VBARP isoforms coding for 69 and 49 kDa polypeptides, respectively, that are primarily localized in the cytoplasm. Functional analysis using short interfering RNA approaches indicate that this gene product is essential for cell survival through its regulation of caspases. Taken together, these results indicate that VBARP is a novel splice variant of ANKHD1 and may play a role in cellular apoptosis (antiapoptotic) and cell survival pathway(s). [source] Analysis of the interaction of 16S rRNA and cytoplasmic membrane with the C-terminal part of the Streptococcus pneumoniae Era GTPaseFEBS JOURNAL, Issue 21 2001Julie Qi Hang Era, an essential GTPase, plays a regulatory role in several cellular processes. The Era protein of Streptococcus pneumoniae has recently been shown to bind to 16S rRNA and the cytoplasmic membrane. However, exact locations of Era responsible for RNA- and membrane-binding were unknown. To identify the regions in Era that interact with the RNA and membrane, the C-terminal part of S. pneumoniae Era was systematically deleted while the N-terminal part, responsible for the GTPase activity of the protein, was kept intact. The resulting truncated Era proteins were purified and characterized. The C-terminal deletion of 9 or 19 amino-acid residues did not affect 16S rRNA-binding activity while further deletions of the C-terminus (29,114 amino-acid residues) abolished the activity. These results indicate that the integrity of the putative KH domain of Era, spanning the amino-acid residues between ,,22,83 from the C-terminus, is required for 16S rRNA-binding. Furthermore, the Era proteins with a deletion up to 45 residues from the C-terminus retained membrane-binding activity, but longer deletions significantly reduced the activity. These results indicate that part of the putative KH domain is also required for membrane-binding. Thus, these results indicate for the first time that the regions critical for the membrane- and 16S rRNA-binding activities of Era overlap. The era gene with a deletion of 9 or 19 codons from its 3, terminus complemented an Escherishia coli mutant strain deficient in Era production whereas the genes with longer deletions failed to do so, thereby indicating that the KH domain is essential for Era function. Taken together, the results of this study indicate that the putative KH domain is required for 16S rRNA-binding activity and that part of the KH domain is also required for membrane-binding activity. The results also suggest that the interaction between Era and 16S rRNA is essential for bacterial growth. [source] Crystallization, microPIXE and preliminary crystallographic analysis of the complex between the third KH domain of hnRNP K and single-stranded DNAACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2004Paul H. Backe hnRNP K is one of the major proteins found in hnRNP particles which are ribonucleoprotein complexes containing proteins and pre-mRNA. hnRNP K contains hnRNP K homology (KH) domains which bind both CT-rich single-stranded DNA (ssDNA) and CU-rich ssRNA. Co-crystallization of the third KH domain of human hnRNP,K with a 15-mer ssDNA gave rod-shaped crystals belonging to the trigonal space group P3121 (unit-cell parameters a = 54.0, c = 149.7,Å) and diffracting to 2.4,Å resolution. MicroPIXE (proton-induced X-ray emission) experiments showed that the crystals contained the complex and that the phosphorus to sulfur atomic ratio was consistent with the asymmetric unit containing three KH3 domains per 15-mer ssDNA. This was confirmed by structure solution by molecular replacement. [source] Crystallization and preliminary X-ray analysis of PH1566, a putative ribosomal RNA-processing factor from the hyperthermophilic archaeon Pyrococcus horikoshii OT3ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2006Min Ze Jia A putative ribosomal RNA-processing factor consisting of two KH domains from Pyrococcus horikoshii OT3 (PH1566; 25,kDa) was crystallized by the sitting-drop vapour-diffusion method using PEG 3000 as the precipitant. The crystals diffracted X-rays to beyond 2.0,Å resolution using a synchrotron-radiation source. The space group of the crystals was determined as primitive orthorhombic P212121, with unit-cell parameters a = 45.9, b = 47.4, c = 95.7,Å. The crystals contain one molecule in the asymmetric unit (VM = 2.5,Å3,Da,1) and have a solvent content of 50%. [source] | ||||||||||