Journal of Microbiology

Journal Articles

Gene deletion and constitutive expression of the pectate lyase gene 1 (MoPL1) lead to diminished virulence of Magnaporthe oryzae: Alex Wegner , Florencia Casanova , Marco Loehrer , Angelina Jordine , Stefan Bohnert , Xinyu Liu , Zhengguang Zhang , Ulrich Schaffrath; J. Microbiol. 2022;60(1):79-88. Published online December 29, 2021; DOI: https://doi.org/10.1007/s12275-022-1074-7

Abstract: Phytopathogenic fungi are known to secrete specific proteins which act as virulence factors and promote host colonization. Some of them are enzymes with plant cell wall degradation capability, like pectate lyases (Pls). In this work, we examined the involvement of Pls in the infection process of Magnaporthe oryzae, the causal agent of rice blast disease. From three Plgenes annotated in the M. oryzae genome, only transcripts of MoPL1 considerably accumulated during the infection process with a peak at 72 h post inoculation. Both, gene deletion and a constitutive expression of MoPL1 in M. oryzae led to a significant reduction in virulence. By contrast, mutants that constitutively expressed an enzymatic inactive version of MoPl1 did not differ in virulence compared to the wild type isolate. This indicates that the enzymatic activity of MoPl1 is responsible for diminished virulence, which is presumably due to degradation products recognized as danger associated molecular patterns (DAMPs), which strengthen the plant immune response. Microscopic analysis of infection sites pointed to an increased plant defense response. Additionally, MoPl1 tagged with mRFP, and not the enzymatic inactive version, focally accumulated in attacked plant cells beneath appressoria and at sites where fungal hyphae transverse from one to another cell. These findings shed new light on the role of pectate lyases during tissue colonization in the necrotrophic stage of M. oryzae's life cycle.

Influences of genetically perturbing synthesis of the typical yellow pigment on conidiation, cell wall integrity, stress tolerance, and cellulase production in Trichoderma reesei: Weixin Zhang , Ning An , Junqi Guo , Zhixing Wang , Xiangfeng Meng , Weifeng Liu; J. Microbiol. 2021;59(4):426-434. Published online January 26, 2021; DOI: https://doi.org/10.1007/s12275-021-0433-0

Abstract: The prominent protein producing workhorse Trichoderma reesei secretes a typical yellow pigment that is synthesized by a gene cluster including two polyketide synthase encoding genes sor1 and sor2. Two transcription factors (YPR1 and YPR2) that are encoded in the same cluster have been shown to regulate the expression of the sor genes. However, the physiological relevance of the yellow pigment synthesis in T. reesei is not completely clear. In this study, a yellow pigment hyper-producer OEypr1 and three yellow pigment non-producers, OEypr1-sor1, Δypr1, and OEypr2, were constructed. Their phenotypic features in mycelial growth, conidiation, cell wall integrity, stress tolerance, and cellulase production were determined. Whereas hyperproduction of the yellow pigment caused significant defects in all the physiological aspects tested, the non-producers showed similar colony growth, but improved conidiation, maintenance of cell wall integrity, and stress tolerance compared to the control strain. Moreover, in contrast to the severely compromised extracellular cellobiohydrolase production in the yellow pigment hyperproducer, loss of the yellow pigment hardly affected induced cellulase gene expression. Our results demonstrate that interfering with the yellow pigment synthesis constitutes an engineering strategy to endow T. reesei with preferred features for industrial application.

Phenotypic characterization of a conserved inner membrane protein YhcB in Escherichia coli: Chul Gi Sung , Umji Choi , Chang-Ro Lee; J. Microbiol. 2020;58(7):598-605. Published online April 22, 2020; DOI: https://doi.org/10.1007/s12275-020-0078-4

Abstract: Although bacteria have diverse membrane proteins, the function of many of them remains unknown or uncertain even in Escherichia coli. In this study, to investigate the function of hypothetical membrane proteins, genome-wide analysis of phenotypes of hypothetical membrane proteins was performed under various envelope stresses. Several genes responsible for adaptation to envelope stresses were identified. Among them, deletion of YhcB, a conserved inner membrane protein of unknown function, caused high sensitivities to various envelope stresses and increased membrane permeability, and caused growth defect under normal growth conditions. Furthermore, yhcB deletion resulted in morphological aberration, such as branched shape, and cell division defects, such as filamentous growth and the generation of chromosome- less cells. The analysis of antibiotic susceptibility showed that the yhcB mutant was highly susceptible to various anti-folate antibiotics. Notably, all phenotypes of the yhcB mutant were completely or significantly restored by YhcB without the transmembrane domain, indicating that the localization of YhcB on the inner membrane is dispensable for its function. Taken together, our results demonstrate that YhcB is involved in cell morphology and cell division in a membrane localization-independent manner.

Published Erratum

Erratum: Development of a Novel Korean H9-Specific rRT-PCR Assay and Its Application for Avian Influenza Virus Surveillance in Korea.: Mingeun Sagong, Yong-Myung Kang, Na Yeong Kim, Eun Bi Noh, Gyeong-Beom Heo, Se-Hee An, Youn-Jeong Lee, Young Ki Choi, Kwang-Nyeong Lee; J. Microbiol. 2024;62(6):489-489.; DOI: https://doi.org/10.1007/s12275-024-00149-6

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