Structural and Functional Annotation of Hypothetical Protein of Fusobacterium nucleatum Strain MJR7757B: An in Silico Approach

Fusobacterium nucleatum is an anaerobic, commensal, gram-negative oral bacterium that is carcinogenic and causes a wide range of human diseases. The present study focused on the analysis of the hypothetical protein, HMPREF3221_01179, derived from F. nucleatum strain MJR7757B, employing various computational methods to anticipate both its structure and functional characteristics. NCBI conserved domain analysis, NCBI BLASTp and MEGA Phylogenetic tree study characterize the target protein as an outer membrane efflux protein (ToIC family) which facilitate the bacterial transmembrane transport. With a molecular weight of 52120.02 Da, an isoelectric point (pI) of 8.33, and an instability index of 29.47, the protein is anticipated to exhibit good solubility in the extracellular space and crucial stability for pharmaceutical applications. The protein’s structure meets quality standards during the construction and refinement of its 3D model. The efflux inhibitor Arginine beta-naphthylamide exhibits a significant binding affinity (-7.1 kcal/mol) to the binding site of the target protein. The in-silico analysis improves the understanding of the protein and facilitates future investigations into therapeutic medication.

Xoryp_08180 of Xanthomonas oryzae pv.oryzicola,Encoding a Hypothetical Protein,is Regulated by HrpG and HrpX and Required for Full Virulence in Rice

Xanthomonas oryzae pv.oryzicola（Xoc） causes a destructive bacterial leaf streak disease in rice.Some of the gene products annotated as hypothetical proteins in the genome of Xoc may contribute to its virulence in rice.A mutant,Mxoc1679,screened from our previous Tn5-tagged mutant library for Xoc strain RS105,showed reduced virulence in rice.In this mutant,a gene named as Xoryp_08180 was disrupted by Tn5 insertion.Xoryp_08180 encodes a 1 306-aa hypothetical protein which is highly conserved in Xanthomonas spp.Non-polar mutation of Xoryp_08180 in RS105 strain led to a significant reduction in bacterial virulence and growth in rice,a delayed hypersensitive response（HR） in non-host tobacco,and a decrease in extracellular protease activity.The deficiencies above were restored to wild-type level in the complementary strain by expressing Xoryp_08180 in trans.In addition,the expression of Xoryp_08180 was repressed in hrpG and hrpX mutants in planta but not in a nutrient-rich condition.These results suggested that Xoryp_08180 is a virulence factor required for extracellular protease production,HR induction and full virulence of Xoc.

HP0953-hypothetical virulence factor overexpresion and localization during Helicobacter pylori infection of gastric epithelium

BACKGROUND The high prevalence and persistence of Helicobacter pylori(H. pylori) infection, as well as the diversity of pathologies related to it, suggest that the virulence factors used by this microorganism are varied. Moreover, as its proteome contains 340hypothetical proteins, it is important to investigate them to completely understand the mechanisms of its virulence and survival. We have previously reported that the hypothetical protein HP0953 is overexpressed during the first hours of adhesion to inert surfaces, under stress conditions, suggesting its role in the environmental survival of this bacterium and perhaps as a virulence factor.AIM To investigate the expression and localization of HP0953 during adhesion to an inert surface and against gastric(AGS) cells.METHODS Expression analysis was performed for HP0953 during H. pylori adhesion. HP0953 expression at 0,3, 12, 24, and 48 h was evaluated and compared using the Kruskal-Wallis equality-of-populations rank test. Recombinant protein was produced and used to obtain polyclonal antibodies for immunolocalization. Immunogold technique was performed on bacterial sections during adherence to inert surfaces and AGS cells, which was analyzed by transmission electron microscopy. HP0953 protein sequence was analyzed to predict the presence of a signal peptide and transmembrane helices, both provided by the ExPASy platform, and using the GLYCOPP platform for glycosylation sites. Different programs, via, I-TASSER, RaptorX, and HHalign-Kbest, were used to perform three-dimensional modeling.RESULTS HP0953 exhibited its maximum expression at 12 h of infection in gastric epithelium cells.Immunogold technique revealed HP0953 localization in the cytoplasm and accumulation in some peripheral areas of the bacterial body, with greater expression when it is close to AGS cells.Bioinformatics analysis revealed the presence of a signal peptide that interacts with the transmembrane region and then allows the release of the protein to the external environment. The programs also showed a similarity with the Tip-alpha protein of H. pylori. Tip-alpha is an exotoxin that penetrates cells and induces tumor necrosis factor alpha production, and HP0953 could have a similar function as posttranslational modification sites were found;modifications in turn require enzymes located in eukaryotic cells. Thus, to be functional, HP0953 may necessarily need to be translocated inside the cell where it can trigger different mechanisms producing cellular damage.CONCLUSION The location of HP0953 around infected cells, the probable posttranslational modifications, and its similarity to an exotoxin suggest that this protein is a virulence factor.