<!DOCTYPE IUCR-ART PUBLIC "IUCr//DTD IUCr article dtd V1.1//EN"><iucr-art jid="D000000" aid="xx0000" access="pay" docsubty="XL" crt="International Union of Crystallography" language="0"><jnlinfo name="Acta Crystallographica Section D" yr="2002" issue="1" volume="58" abbrtitle="Acta Cryst. D" coden="ABCRE6" editor="Jenny P. Glusker" issn="0907-4449" fpage="0" lpage="0"><fm><atl>Crystallization of the novel flavodoxine-like protein, WrbA, - on the way to three-dimensional structure
<aff><oid id="a">Institute of Physical Biology, University of South Bohemia at Ceske Budejovice, Zamek 136, CZ-373 33 Nove Hrady, <cny>Czech Republic</cny></aff>, a'">Institute of Physical Biology, University of South Bohemia at Ceske Budejovice and Institute of Landscape Ecology, Academy of Science of the Czech Republic, Zamek 136, CZ-373 33 Nove Hrady, <cny>Czech Republic</cny></aff>, <aff><oid id="b">Institute of Chemistry, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, <cny>Austria</cny></aff>, and <aff><oid id="c">Chemistry Department, Priceton University, Washington Rd and William St, Princeton, NJ 08544-1009, <cny>USA</cny></aff></aug>.
Keywords: flavodoxine-like protein; tryptophan-repressor binding protein; WrbA apoprotein; WrbA holoprotein; FMN; standard crystallization techniques; advanced crystallization techniques</atl>
Tryptophan (W)-repressor binding protein A, WrbA, identified as an E. coli stationary-phase protein was named for its reported effect on the interaction between tryptophan repressor and DNA . Later work  showed that this effect was non-specific, leaving the physiological role of WrbA unknown. According to sequence analysis and homology modeling  WrbA was identified as the founding member of a new family of flavodoxin-like proteins, which displays low but structurally significant sequence similarity with the flavodoxins. The members of WrbA family are predicted to share the open, twisted a/b flavodoxin fold, but with a short conserved insertion unique for the new family. This structure motif could account for experimental observations that some family members are dimeric in solution, including also finding that WrbA creates a dimer-tetramer equilibrium at micromolar concentrations . Unlike typical flavodoxins , these proteins bind FMN relatively weakly but still specifically. The computer analysis  indicated some structural differences in the flavin-binding pocket, which may explain the lower affinity of WrbA for FMN. Due to these peculiarities the structural analysis may aid in understanding the physiological roles of WrbA family members. These factors motivated our research for diffraction-quality crystals.
Purified WrbA apoprotein and holoprotein were used for crystallization trials. Standard and advanced crystallization techniques were applied to crystallize mentioned proteins. WrbA apoprotein crystals grown in capillaries were measured directly at synchrotron DESY (beamline X13) in Hamburg (Germany). Crystals diffracted to a resolution of 2.2Å. Attempts with variable growing conditions are performed to improve quality of apo- and holoprotein crystals.
This work is supported by grants of the Ministry of Education of the Czech Republic (projects KONTAKT ME640 and LN00A141) to I.K.S. and by NSF grant INT-03-09049 to J.C.
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