CELL2007 Molecular Exploration Project
Group 7
When the Homo sapiens TESK1 sequence is run through Pfam-A, it is shown that the protein contains only one conserved functional domain, the Protein Kinase domain. This domain starts at amino acid 57 and ends at 311. There is a very high posterior probability (degree of confidence) between the TESK1 sequence and the Protein Kinase domain and the Expect (E) value, is very small (Figure 13) [1]. This Protein Kinase domain is common to all 3 isoforms [2].
A protein kinase domain is the catalytic domain of Protein Kinases. These are enzymes that transfer phosphate groups onto proteins (called phosphorylation) to activate or inactivate many cellular processes. For more information follow this link to the Pfam summary of the Protein Kinase domain which uses the Wikipedia article on the Protein Kinase domain and the Pfam and InterPro entry:
When the sequence is run in BLAST, It is shown that there are several possible active sites, ATP binding sites, and polypeptide binding sites shown (Figure 14). This is also shown diagrammatically by InterPro in Figure 15. Of these sites, the UniProt database specifically describes an ATP binding site at position 86, a Proton accepting active site at position 175, and a 9 amino acid long sequence from postion 63 to 71 that acts as a nucleotide binding region. [5].
As mentioned in the introduction, a study by Toshima et al. found that the catalytic loop in the VIB subdomain of the protein kinase domain contains an unusual DLTSKN sequence not related to the consensus sequence in other serine/threonine and tyrosine kinases. However, in vitro studies have shown that it still maintains serine/threonine, and tyrosine kinase activity. They showed that Serine-215 is the site of serine autophosphorylation as mutagenesis studies have found that mutation of Serine-215 in the TESK1 activation loop to alanine or glatamic acid abolishes autophosphorylation activity [6].
The PKc_TESK subfamily phosphorylates Serine/Threonine and sometimes Tyrosine, and it’s main target is cofilin. It is most closely related to the PKc_LIMK_like_unk and STKc_LIMK, and evolved from STKc_LIMK (Figure 16). The NCBI accession code for the PKc_TESK subfamily is cd14155. Here is the link to the web page for more information:
http://www.ncbi.nlm.nih.gov/Structure/cdd/cddsrv.cgi?ascbin=8&maxaln=10&seltype=2&uid=cd14155
Figure 13: Pfam Domain analysis. Taken from the Pfam server. The green highlight indicates a 100% or close to 100% posterior probability of the residue.
[1] The Pfam protein families database: R.D. Finn, A. Bateman, J. Clements, P. Coggill, R.Y. Eberhardt, S.R. Eddy, A. Heger, K. Hetherington, L. Holm, J. Mistry, E.L.L. Sonnhammer, J. Tate, M. PuntaNucleic Acids Research (2014) Database Issue 42:D222-D230.
Figure 14: Putative Conserved Domains of TESK1. Taken from the BLAST server.
[3] Stephen F. Altschul, Thomas L. Madden, Alejandro A. Schäffer, Jinghui Zhang, Zheng Zhang, Webb Miller, and David J. Lipman (1997), "Gapped BLAST and PSI-BLAST: a new generation of protein database search programs", Nucleic Acids Res. 25:3389-3402.
Figure 16: CD Tree. Sub-Domain Hierachy of TESK. Adapted from NCBI Website.
[7] Marchler-Bauer A, Zheng C, Chitsaz F, Derbyshire MK, Geer LY, Geer RC, Gonzales NR, Gwadz M, Hurwitz DI, Lanczycki CJ, Lu F, Lu S, Marchler GH, Song JS, Thanki N, Yamashita RA, Zhang D, Bryant SH. CDD: conserved domains and protein three-dimensional structure. Nucleic Acids Res. 2013 Jan 1;41(D1):D348-52. 2012 Nov 28.
Domain Analysis
As well as the Protein Kinase domain, both the 3% Transmambrane helix found by PHYRE2 and evidence from Psort suggests that all 3 isoforms have a single transmembrane domain in the region of amino acids 236 to 250.
Figure 15: Conserved domain of TESK1 accompanied by representaions of catalytic domains, binding sites and active sites, Taken from the InterPro database, accession code Q15569.
[4] InterPro website http://www.ebi.ac.uk/interpro/protein/Q15569 accessed 15/03/15