Helicobacter muricola sp. nov., a novel Helicobacter species isolated from the ceca and feces of Korean wild mouse (Mus musculus molossinus)

A slowly growing microaerophilic Helicobacter strain was isolated from the ceca and fecal pellets of Korean wild mice (Mus musculus molossinus). This bacterial strain possessed a pair of nonsheathed bipolar flagella, was positive for urease, catalase and oxidase, and reduced nitrate to nitrite. It proved susceptible to nalidixic acid and resistant to cephalodine, and did not hydrolyze hippurate. On the basis of phenotypic characteristics and 16S rRNA gene sequence analysis, the isolate represents a new species of the genus Helicobacter, for which the name Helicobacter muricola sp. nov. is proposed; the type strain of the new species is w-06T.     

Identification of Staphylococcus xylosus isolated from C57BL/6J-Nos2(tm1Lau) mice with dermatitis

Coagulase negative staphylococci (CNS) are significant pathogens, particularly in medical device related infections and in immunocompromised patients. Five CNS strains were isolated from 5 NOS2 knockout mice with dermatitis. Histologically, granulomatous dermatitis was found in the skin around the ear with epidermal ulceration. Dermal lesions included pustules, necrosis, and accumulations of neutrophils and macrophages. Isolates of the bacterial strains were identified to be Staphylococcus xylosus by the API STAPH kit and 16S-23S intergenic transcribed spacer-PCR. These results demonstrate the potential of this organism to be an opportunistic pathogen in immunocompromised mice.     

Fanconi anemia protein complex is a novel target of the IKK signalsome

Fanconi anemia (FA), a genetic disorder predisposing to aplastic anemia and cancer, is characterized by hypersensitivity to DNA-damaging agents and oxidative stress. Five of the cloned FA proteins (FANCA, FANCC, FANCE, FANCF, FANCG) appear to be involved in a common functional pathway that is required for the monoubiquitination of a sixth gene product, FANCD2. Here, we report that FANCA associates with the IkappaB kinase (IKK) signalsome via interaction with IKK2. Components of the FANCA complex undergo rapid, stimulus-dependent changes in phosphorylation, which are blocked by kinase-inactive IKK2 (IKK2 K > M). When exposed to mitomycin C, cells expressing IKK2 K > M develop a cell cycle abnormality characteristic of FA. Thus, FANCA may function to recruit IKK2, thus providing the cell a means of rapidly responding to stress.     

Mutational analysis of human hydroxysteroid sulfotransferase SULT2B1 isoforms reveals that exon 1B of the SULT2B1 gene produces cholesterol sulfotransferase,whereas exon 1A yields pregnenolone sulfotransferase

As a result of an alternative exon 1, the gene for human hydroxysteroid sulfotransferase (SULTB1) encodes for two peptides differing only at their amino termini. The SULT2B1b isoform preferentially sulfonates cholesterol. Conversely, the SULT2B1a isoform avidly sulfonates pregnenolone but not cholesterol. The outstanding structural feature that distinguishes the SULT2B1 isoforms from the prototypical SULT2A1 isozyme is the presence of extended amino- and carboxyl-terminal ends in the former. Investigating the functional significance of this unique characteristic reveals that removal of 53 amino acids from the relatively long carboxyl-terminal end that is common to both SULT2B1 isoforms has no effect on the catalytic activity of either isoform. On the other hand, removal of 23 amino acids from the amino-terminal end that is unique to SULT2B1b results in loss of cholesterol sulfotransferase activity, whereas removal of 8 amino acids from the amino-terminal end that is unique to SULT2B1a has no effect on pregnenolone sulfotransferase activity. Deletion analysis along with site-directed mutagenesis of SULT2B1b reveal that the amino acid segment 19-23 residues from the amino terminus and particularly isoleucines at positions 21 and 23 are crucial for cholesterol catalysis. In the gene for SULT2B1, exon 1B encodes for only the unique amino-terminal region of SULT2B1b; however, exon 1A encodes for the unique amino-terminal end of SULT2B1a plus an additional 48 amino acids. Thus, if the gene for SULT2B1 employs exon 1B, cholesterol sulfotransferase is synthesized, whereas if exon 1A is used, pregnenolone sulfotransferase is produced.     

The cystic fibrosis transmembrane conductance regulator interacts with and regulates the activity of the HCO3- salvage transporter human Na+-HCO3- cotransport isoform 3

Cystic fibrosis transmembrane conductance regulator (CFTR) regulates both HCO(3)(-) secretion and HCO(3)(-) salvage in secretory epithelia. At least two luminal transporters mediate HCO(3)(-) salvage, the Na(+)/H(+) exchanger (NHE3) and the Na(+)-HCO(3)(-) cotransport (NBC3). In a previous work, we show that CFTR interacts with NHE3 to regulate its activity (Ahn, W., Kim, K. W., Lee, J. A., Kim, J. Y., Choi, J. Y., Moe, O. M., Milgram, S. L., Muallem, S., and Lee, M. G. (2001) J. Biol. Chem. 276, 17236-17243). In this work, we report that transient or stable expression of human NBC3 (hNBC3) in HEK cells resulted in a Na(+)-dependent, DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid)- and 5-ethylisopropylamiloride-insensitive HCO(3)(-) transport. Stimulation of CFTR with forskolin markedly inhibited NBC3 activity. This inhibition was prevented by the inhibition of protein kinase A. NBC3 and CFTR could be reciprocally coimmunoprecipitated from transfected HEK cells and from the native pancreas and submandibular and parotid glands. Precipitation of NBC3 or CFTR from transfected HEK293 cells and from the pancreas and submandibular gland also coimmunoprecipitated EBP50. Glutathione S-transferase-EBP50 pulled down CFTR and hNBC3 from cell lysates when expressed individually and as a complex when expressed together. Notably, the deletion of the C-terminal PDZ binding motifs of CFTR or hNBC3 prevented coimmunoprecipitation of the proteins and inhibition of hNBC3 activity by CFTR. We conclude that CFTR and NBC3 reside in the same HCO(3)(-)-transporting complex with the aid of PDZ domain-containing scaffolds, and this interaction is essential for regulation of NBC3 activity by CFTR. Furthermore, these findings add additional evidence for the suggestion that CFTR regulates the overall trans-cellular HCO(3)(-) transport by regulating the activity of all luminal HCO(3)(-) secretion and salvage mechanisms of secretory epithelial cells.     

The Hexapeptide inhibitor of Galbeta 1,3GalNAc-specific alpha 2,3-sialyltransferase as a generic inhibitor of sialyltransferases

The mammalian Galbeta1,3GalNAc-specific alpha2,3-sialyltransferase (ST3Gal I) was expressed as a secreted glycoprotein in High Five (Trichoplusia ni) cells. Using this recombinant ST3Gal I, we screened the synthetic hexapeptide combinatorial library to explore a sialyltransferase inhibitor. We found that the hexapeptide, NH(2)-GNWWWW, exhibited the most strong inhibition of ST3Gal I among five different hexapeptides that were finally selected. The kinetic analysis of ST3Gal I inhibition demonstrated that this hexapeptide could act as a competitive inhibitor (K(i) = 1.1 microm) on CMP-NeuAc binding to the enzyme. Moreover, the hexapeptide was shown to strongly inhibit both N-glycan-specific alpha2,3- and alpha2,6-sialyltranferase in vitro, suggesting that this peptide may inhibit the broad range of sialyltransferases regardless of their linkage specificity. The inhibitory activity in vivo was investigated by RCA-I lectin blot analyses and by metabolic d-[6-(3)H]GlcNH(2) radiolabeling analyses of N- and O-linked oligosaccharides in Chines hamster ovary cells. Our results demonstrate that the hexapeptide can act as a generic inhibitor of the N- and O-glycan-specific sialyltransferases in mammalian cells, which results in the significantly reduced NeuAc expression on cellular glycoproteins in vivo.