1e20: Difference between revisions

==Overview==

BACKGROUND: The Arabidopsis thaliana HAL3 gene product encodes for an, FMN-binding protein (AtHal3) that is related to plant growth and salt and, osmotic tolerance. AtHal3 shows sequence homology to ScHal3, a regulatory, subunit of the Saccharomyces cerevisae serine/threonine phosphatase PPz1., It has been proposed that AtHal3 and ScHal3 have similar roles in cellular, physiology, as Arabidopsis transgenic plants that overexpress AtHal3 and, yeast cells that overexpress ScHal3 display similar phenotypes of improved, salt tolerance. The enzymatic activity of AtHal3 has not been, investigated. However, the AtHal3 sequence is homologous to that of EpiD, a flavoprotein from Staphylococcus epidermidis that recognizes a peptidic, substrate and subsequently catalyzes the alpha, beta-dehydrogenation of, its C-terminal cysteine residue. RESULTS: The X-ray structure of AtHal3 at, 2 A resolution reveals that the biological unit is a trimer. Each protomer, adopts an alpha/beta Rossmann fold consisting of a six-stranded parallel, beta sheet flanked by two layers of alpha helices. The FMN-binding site of, AtHal3 contains all the structural requirements of the flavoenzymes that, catalyze dehydrogenation reactions. Comparison of the amino acid sequences, of AtHal3, ScHal3 and EpiD reveals that a significant number of residues, involved in trimer formation, the active site, and FMN binding are, conserved. This observation suggests that ScHal3 and EpiD might also be, trimers, having a similar structure and function to AtHal3. CONCLUSIONS:, Structural comparisons of AtHal3 with other FMN-binding proteins show that, AtHal3 defines a new subgroup of this protein family that is involved in, signal transduction. Analysis of the structure of AtHal3 indicates that, this protein is designed to interact with another cellular component and, to subsequently catalyze the alpha,beta-dehydrogenation of a peptidyl, cysteine. Structural data from AtHal3, together with physiological and, biochemical information from ScHal3 and EpiD, allow us to propose a model, for the recognition and regulation of AtHal3/ScHal3 cellular partners.

 

1E20 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana] with <scene name='pdbligand=NI:'>NI</scene>, <scene name='pdbligand=FMN:'>FMN</scene> and <scene name='pdbligand=BME:'>BME</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Known structural/functional Site: <scene name='pdbsite=AC1:Fmn+Binding+Site'>AC1</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1E20 OCA].  

 

==Reference==

The X-ray structure of the FMN-binding protein AtHal3 provides the structural basis for the activity of a regulatory subunit involved in signal transduction., Albert A, Martinez-Ripoll M, Espinosa-Ruiz A, Yenush L, Culianez-Macia FA, Serrano R, Structure. 2000 Sep 15;8(9):961-9. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10986463 10986463]

[[Category: Single protein]]

[[Category: Albert, A.]]

[[Category: Culianez-Macia, F.A.]]

[[Category: Espinosa-Ruiz, A.]]

[[Category: Martinez-Ripoll, M.]]

[[Category: Serrano, R.]]

[[Category: Yenush, L.]]

[[Category: BME]]