Journal of Microbiology

Journal Article

Alpha‑Hemolysin from Staphylococcus aureus Obstructs Yeast‑Hyphae Switching and Diminishes Pathogenicity in Candida albicans: Xiaoyu Yu , Yinhe Mao , Guangbo Li , Xianwei Wu , Qiankun Xuan , Simin Yang , Xiaoqing Chen , Qi Cao , Jian Guo , Jinhu Guo , Wenjuan Wu; J. Microbiol. 2023;61(2):233-243. Published online February 9, 2023; DOI: https://doi.org/10.1007/s12275-022-00006-4

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Abstract: The use of antibiotics can disrupt the body’s natural balance and increase the susteptibility of patients towards fungal infections. Candida albicans is a dimorphic opportunistic fungal pathogen with niches similar to those of bacteria. Our aim was to study the interaction between this pathogen and bacteria to facilitate the control of C. albicans infection. Alpha-hemolysin (Hla), a protein secreted from Staphylococcus aureus, causes cell wall damage and impedes the yeast–hyphae transition in C. albicans. Mechanistically, Hla stimulation triggered the formation of reactive oxygen species that damaged the cell wall and mitochondria of C. albicans. The cell cycle was arrested in the G0/G1 phase, CDC42 was downregulated, and Ywp1 was upregulated, disrupting yeast hyphae switching. Subsequently, hyphae development was inhibited. In mouse models, C. albicans pretreated with Hla reduced the C. albicans burden in skin and vaginal mucosal infections, suggesting that S. aureus Hla can inhibit hyphal development and reduce the pathogenicity of candidiasis in vivo.

Review

MINIREVIEW] Multilayered regulations of RIG-I in the anti-viral signaling pathway: Nari Kim , Hesung Now , Nhung T.H. Nguyen , Joo-Yeon Yoo; J. Microbiol. 2016;54(9):583-587. Published online August 31, 2016; DOI: https://doi.org/10.1007/s12275-016-6322-2

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14 Citations

Abstract: RIG-I is a cytosolic receptor recognizing virus-specific RNA structures and initiates an antiviral signaling that induces the production of interferons and proinflammatory cytokines. Because inappropriate RIG-I signaling affects either viral clearance or immune toxicity, multiple regulations of RIG-I have been investigated since its discovery as the viral RNA detector. In this review, we describe the recent progress in research on the regulation of RIG-I activity or abundance. Specifically, we focus on the mechanism that modulates RIGI- dependent antiviral response through post-translational modifications of or protein-protein interactions with RIG-I.

Research Support, Non-U.S. Gov'ts

Protein-Protein Interactions between Histidine Kinases and Response Regulators of Mycobacterium tuberculosis H37Rv: Ha-Na Lee , Kwang-Eun Jung , In-Jeong Ko , Hyung Suk Baik , Jeong-Il Oh; J. Microbiol. 2012;50(2):270-277. Published online April 27, 2012; DOI: https://doi.org/10.1007/s12275-012-2050-4

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25 Citations

Abstract: Using yeast two-hybrid assay, we investigated protein-protein interactions between all orthologous histidine kinase (HK)/response regulator (RR) pairs of M. tuberculosis H37Rv and identified potential protein-protein interactions between a noncognate HK/RR pair, DosT/NarL. The protein interaction between DosT and NarL was verified by phosphotransfer reaction from DosT to NarL. Furthermore, we found that the DosT and DosS HKs, which share considerable sequence similarities to each other and form a twocomponent system with the DosR RR, have different crossinteraction capabilities with NarL: DosT interacted with NarL, while DosS did not. The dimerization domains of DosT and DosS were shown to be sufficient to confer specificity for DosR, and the different cross-interaction abilities of DosS and DosT with NarL were demonstrated to be attributable to variations in the amino acid sequences of the α2-helices of their dimerization domains.

Dynamical Analysis of Yeast Protein Interaction Network During the Sake Brewing Process: Mitra Mirzarezaee , Mehdi Sadeghi , Babak N. Araabi; J. Microbiol. 2011;49(6):965-973. Published online December 28, 2011; DOI: https://doi.org/10.1007/s12275-011-1194-y

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Abstract: Proteins interact with each other for performing essential functions of an organism. They change partners to get involved in various processes at different times or locations. Studying variations of protein interactions within a specific process would help better understand the dynamic features of the protein interactions and their functions. We studied the protein interaction network of Saccharomyces cerevisiae (yeast) during the brewing of Japanese sake. In this process, yeast cells are exposed to several stresses. Analysis of protein interaction networks of yeast during this process helps to understand how protein interactions of yeast change during the sake brewing process. We used gene expression profiles of yeast cells for this purpose. Results of our experiments revealed some characteristics and behaviors of yeast hubs and non-hubs and their dynamical changes during the brewing process. We found that just a small portion of the proteins (12.8 to 21.6%) is responsible for the functional changes of the proteins in the sake brewing process. The changes in the number of edges and hubs of the yeast protein interaction networks increase in the first stages of the process and it then decreases at the final stages.

Journal Article

Carbon Source Dependent Dynamics of the Ccr4-Not Complex in Saccharomyces cerevisiae: Joakim Norbeck; J. Microbiol. 2008;46(6):692-696. Published online December 24, 2008; DOI: https://doi.org/10.1007/s12275-008-0122-2

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Abstract: We have investigated the composition of the conserved Ccr4-Not complex during different physiological states of Saccharomyces cerevisiae. Major changes were found, most notably in the expression of the central scaffold protein Not1p, which was strongly reduced in the absence of glucose. The low expression of Not1p was also evident from the inability of Pop2p to co-purify Not1p in cells from cultures lacking glucose. However, Not1p was still essential under conditions of low expression. The downregulation of Not1p indicates that many of the Ccr4-Not complex components are likely to have roles outside of the complex. We suggest that the use of different carbon sources will be a good starting point to unravel these functions.

Research Support, Non-U.S. Gov't

Cyanobacterial Hybrid Kinase Sll0043 Regulates Phototaxis by Suppressing Pilin and Twitching Motility Protein: Bong-Jeong Shin , Jeehyun Oh , Sungsoo Kang , Young-Ho Chung , Young Mok Park , Young Hwan Kim , Seungil Kim , Jong Bhak , Jong-Soon Choi; J. Microbiol. 2008;46(3):300-308. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0212-6

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8 Citations

Abstract: The unicellular cyanobacterium Synechocystis sp. PCC 6803 glides toward a light source through the interplay of positive phototaxis genes and proteins. In genetic analysis, the complete disruption of the hybrid sensory kinase sll0043 produced negative phototaxis. Furthermore, Sll0043 was found to be a hub protein by in silico prediction of protein-protein interaction, in which Sll0043 was predominantly linked to seven two-component proteins with high confidence. To understand the regulation and networking of positive phototaxis proteins, the proteomic profile of the sll0043 mutant was compared to that of wild-type. In the sll0043 mutant, 18 spots corresponding to 15 unique proteins were altered by 1.3 to 59 fold; the spots were identified by 2-DE/MALDI-MS analysis. Down-regulated proteins in the sll0043 null-mutant included chaperonins, superoxide dismutase, and phycocyanin β-subunit. In contrast, nine proteins involved in photosynthesis, translation, regulatory function, and other functions were up-regulated. In particular, a twitching motility protein (PilT1) was induced over 2-fold in sll0043 mutant. Moreover, semiquantitative and quantitative RT-PCR analysis revealed that pilin (pilA1), pili motor (pilT1), and pili switch gene (pilT2) were significantly increased in sll0043 mutant. These results suggest that the hybrid kinase Sll0043 regulates positive phototaxis by suppressing the expression of pili biosynthesis and regulatory genes and through the interplay with positive phototaxis/motility two-component proteins.

Identification of a cellular protein interacting with murine retrovirus Gag polyproteins: Choi , Won Ja; J. Microbiol. 1996;34(4):311-315.

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Abstract: The retroviral Gag polyprotein directs the assembly of virion particles and plays an important role in some events after entry into a host cell. The Gag polyprotein of a virus mixture is responsible for inducing murine acquired immunodeficiency syndrome (MAIDS) when injected into susceptible strains of mice. In order to identify the host cellular proteins which interact with the MAIDS virus Gag proteins and possibly mediate the function of the Gag proteins, mouse T-cell leukemic cDNA expression library was screened using the yeast GAL4 two hybrid system. Of 11 individual positive clones, the clone Y1 was selected for the study of protein-protein interaction. Its DNA sequence revealed that it was an exact match to the murine SH3 domain-containing protein SH3P8. It is expressed as 2.4 kbp transcripts in testis at higher levels and in various tissues tested at lower levels. Glutathione S-transferase-Y1 fusion protein binds tightly to Pr60^def-gag as well as Pr 65^eco-gag.

Use of the Yeast 1.5-Hybrid System to Detect DNA-Protein-Protein Interactions: Sook-Kyung Kim , Jin Hee Han; J. Microbiol. 2000;38(2):113-116.

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Abstract: Escherichia coli F plasmid partition apparatus is composed of two trans-acting proteins (SopA and SopB) and one cis-acting DNA sequence (sopC). The SopB-sopC complex has been suggested to serve a centromere-like function through its interaction with chromosomally encoded proteins which remain to be identified. In this paper, we are introducing a new yeast 1.5-hybrid system which assembles the two-hybrid and one-hybrid system as a mean to find an additional component of the F plasmid partition system, interacting with DNA (sopC)-bound SopB protein. The result indicates that this system is a promising one, capable of selecting an interacting component.

Regulation of Glycogen Concentration by the Histidine-Containing Phosphocarrier Protein HPr in Escherichia coli: Byoung-Mo Koo , Yeong-Jae Seok; J. Microbiol. 2001;39(1):24-30.

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Abstract: In addition to effecting the catalysis of sugar uptake, the bacterial phosphoenolpyruvate:sugar phosphotransferase system regulates a variety of physiological processes. In a previous paper [Seok et al., (1997) J. Biol. Chem. 272, 26511-26521], we reported the interaction with and allosteric regulation of Escherichia coli glycogen phosphorylase activity by the histidine-containing phosphocarrier protein HPr in vitro. Here, we show that the specific interaction between HPr and glycogen phosphorylase occurs in vivo. To address the physiological role of the HPr-glycogen phosphorylase complex, intracellular glycogen levels were measured in E. coli strains transformed with various plasmids. While glycogen accumulated during the transition between exponential and stationary growth phases in wildtype cells, it did not accumulate in cells overproducing HPr or its inactive mutant regardless of the growth stage. From these results, we conclude that HPr mediates crosstalk between sugar uptake through the phosphoenolpyruvate:sugar phosphotransferase system and glycogen breakdown. The evolutionary significance of the HPr-glycogen phosphorylase complex is suggested.

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