Disease relevance of spvB

• By using a lacZ reporter transcriptional fusion to the spvB structural gene on the single-copy virulence plasmid, it was found that while spvB transcription was induced in stationary-phase cultures, the induced level of expression was lower than that reported for the spv system in other serovars of Salmonella [1].
• Complementation experiments performed with the cloned katF gene confirmed that KatF is required for the expression of the S. typhimurium virulence gene spvB in E. coli [2].
• We also suggest that the diffusion of these hydrophilic compounds most likely occurs through water-filled pores present in the cell wall of gram-negative bacteria [3].
• The biofilters were also challenged with 1 microm fluorescent microspheres with hydrophobic and hydrophilic surface characteristics and bacteriophages (Salmonella typhimurium 28B) [4].
• However by choosing a hydrophilic (Salmonella typhimurium ATCC 14028) and a hydrophobic bacterium (Acinetobacter calcoaceticus var. anitratus RR 8212/113), one could hope to obtain a quite representative idea about the extraction of contaminating gram-negative micro-organisms [5].

High impact information on spvB

• For transport, each binding protein interacts with a cognate membrane complex consisting of two hydrophobic proteins and two subunits of a hydrophilic ATPase [6].
• Water molecules satisfy the hydrogen bonding ability of the hydrophilic side chains of the binding site in a manner which is reminiscent of the sugars' hydrogen-bonding patterns [7].
• However, the localization of the putative first hydrophilic loop and the NH2 terminus was not possible because the beta-lactamase fusions in this region were shown to be unreliable indicators of the topology of RhaT [8].
• The structural conservation of the components is discussed, and a role for a hydrophilic loop containing a conserved sequence (the EAA loop) is proposed [9].
• These results show that although the mannitol Enzyme II is an integral membrane protein, a considerable portion of its polypeptide chain must also extend into a hydrophilic environment, presumably the cytoplasm [10].

Biological context of spvB

• Wild-type (i.e., 10-fold-lower) levels of spvB expression were restored by providing active copies of crp or cya on recombinant plasmids [1].
• The protein product, BlaR, has a hydrophilic carboxy region that binds beta-lactams and shows high sequence homology to the class D beta-lactamases, particularly the OXA-2 beta-lactamase of Salmonella typhimurium [11].
• The deduced amino acid sequences of the wild-type FliK proteins of S. typhimurium and E. coli correspond to molecular masses of 41,748 and 39,246 Da, respectively, and are fairly hydrophilic [12].
• From the DNA sequence of tctD, the predicted gene product was hydrophilic and shared distinct homologies with other globally regulated transcriptional activators such as OmpR and NtrC [13].
• Such results support the view that one important function of IgG antibody and complement is to decrease the hydrophilic properties of the bacteria which is thought to be a prerequisite for phagocytosis [14].

Anatomical context of spvB

• Activity of RpoS also increases after bacterial entry into both macrophages and epithelial cells, as demonstrated by the induction of the rpoS-regulated genes katE and spvB [15].
• These observations led us to conclude that the outer membrane, rather than peptidoglycan, sets the size limit for the penetration of uncharged, hydrophilic molecules through the E. coli or S. typhimurium cell wall [16].
• To quantitative the extent of penetration of these hydrophilic compounds into the periplasm, the radioactivity of the cell pellet was determined after centrifugation [3].
• Thus agents with the potential for reacting with cellular DNA, inducing mutations in Salmonella and clastogenicity in cultured cells were characteristically significantly more hydrophilic than agents which did not induce such effects [17].
• Hydropathicity plots predict that the presumed surface location of the hydrophilic c/e1-region within the core particle may alter following insertion of hydrophobic residues constituting the CTL epitopes, thereby compromising their presentation to the afferent immune system [18].

Associations of spvB with chemical compounds

• These data suggest that defects in LPS core structure other than loss of heptose moieties may also be important in loss of resistance to large, hydrophilic molecules such as glycopeptides [19].
• Experiments with phospholipid bilayers showed that the addition of PEG-lipids (containing covalently attached hydrophilic polymers) had little effect on permeability and binding rates, whereas the addition of cholesterol reduced permeability and slowed binding to levels approaching those of LPS [20].
• The data indicated that the lipopolysaccharide layer might form a permeability barrier for hydrophobic quinolones such as nalidixic acid but not for hydrophilic quinolones such as norfloxacin and ciprofloxacin [21].
• Aztreonam exposure decreased the liability of the bacteria to hydrophilic interactions in an aqueous two-phase partitioning system [22].
• Other lipophilic scavengers such as alpha-tocopherol and N,N'-diphenyl-1,4-phenylenediamine exerted only moderate effects, the hydrophilic scavenger trolox was inactive [23].

Regulatory relationships of spvB

• In contrast, spvB transcription in stationary-phase cultures was enhanced by 10-fold in mutants deficient in crp-encoded CRP or cya-encoded adenylate cyclase [1].

Other interactions of spvB

• Enhanced spvB transcription was not seen in crp or cya mutants in the absence of a functional spvR positive regulatory gene, showing that the cAMP-CRP system acted on spvB expression either in conjunction with or via SpvR [1].
• Deletion of a 320-bp EcoRI-ApaI segment that contains both start sites abolished expression of the downstream spvB and spvC genes [24].

Analytical, diagnostic and therapeutic context of spvB

• First, a multiplex PCR amplification of hns, spvB, vvh, ctx and tl was developed enabling simultaneous detection of total Salmonella enterica serotype Typhimurium, Vibrio vulnificus, Vibrio cholerae and Vibrio parahaemolyticus from both pure cultures and seeded oysters [25].
• Membrane antigens are also characterized with regard to their amphiphilic or hydrophilic properties by charge-shift crossed immunoelectrophoresis [26].
• Added microspheres were removed at 97-99% (hydrophobic) and 85-89% (hydrophilic) after 5 hydraulic residence times (HRT) and microspheres retained in the biofilter media were slowly detaching into the filtrate for a long time after the addition [4].
• Due to the low sensitivity of genotoxicity test systems, PAD-1 resin was used as solid phase to concentrate less hydrophilic compounds from aqueous soil extracts [27].

References