Taxonomic distribution of proteins containing ProQ domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing ProQ domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Crystal structure of the bacterial conjugation repressor finO.

Ghetu AF, Gubbins MJ, Frost LS, Glover JN
Nat Struct Biol. 2000; 7: 565-9

The conjugative transfer of F-like plasmids is repressed by FinO, an RNAbinding protein. FinO interacts with the F-plasmid encoded traJ mRNA andits antisense RNA, FinP, stabilizing FinP against endonucleolyticdegradation and facilitating sense-antisense RNA recognition. Here wepresent the 2.0 A resolution X-ray crystal structure of FinO, lacking itsflexible N-terminal extension. FinO adopts a novel, elongated, largelyhelical conformation. An N-terminal region, previously shown to contactRNA, forms a positively charged alpha-helix (helix 1) that protrudes 45 Afrom the central core of FinO. A C-terminal region of FinO that isimplicated in RNA interactions also extends out from the central body ofthe protein, adopting a helical conformation and packing against the baseof the N-terminal helix. A highly positively charged patch on the surfaceof the FinO core may present another RNA binding surface. The results ofan in vitro RNA duplexing assay demonstrate that the flexible N-terminalregion of FinO plays a key role in FinP-traJ RNA recognition, and supportsour proposal that this region and the N-terminus of helix 1 interact withand stabilize paired, complementary RNA loops in a kissing complex.

Protein ProQ influences osmotic activation of compatible solutetransporter ProP in Escherichia coli K-12.

Kunte HJ, Crane RA, Culham DE, Richmond D, Wood JM
J Bacteriol. 1999; 181: 1537-43

ProP is an osmoregulatory compatible solute transporter in Escherichiacoli K-12. Mutation proQ220::Tn5 decreased the rate constant for and theextent of ProP activation by an osmotic upshift but did not alter proPtranscription or the ProP protein level. Allele proQ220::Tn5 was isolated,and the proQ sequence was determined. Locus proQ is upstream from prc(tsp) at 41.2 centisomes on the genetic map. The proQ220::Tn5 and prcphenotypes were different, however. Gene proQ is predicted to encode a232-amino-acid, basic, hydrophilic protein (molecular mass, 25,876 Da;calculated isoelectric point, 9.66; 32% D, E, R, or K; 54.5% polar aminoacids). The insertion of PCR-amplified proQ into vector pBAD24 produced aplasmid containing the wild-type proQ open reading frame, the expressionof which yielded a soluble protein with an apparent molecular mass of 30kDa. Antibodies raised against the overexpressed ProQ protein detectedcross-reactive material in proQ+ bacteria but not in proQ220::Tn5bacteria. ProQ may be a structural element that influences the osmoticactivation of ProP at a posttranslational level.