Journal of Microbiology

Journal Article

Minimal amino acids in the I/LWEQ domain required for anterior/posterior localization in Dictyostelium: Hyeseon Kim , Dong-Yeop Shin , Taeck Joong Jeon; J. Microbiol. 2017;55(5):366-372. Published online January 26, 2017; DOI: https://doi.org/10.1007/s12275-017-6550-0

Abstract: Establishment of cell polarity is mediated by a series of signal-ing molecules that are asymmetrically activated or localized in the cell upon extracellular stimulation. To understand the mechanism that mediates anterior/posterior asymmetric localization of RapGAP3 during migration, we determined the minimally required amino acids in the I/LWEQ domain that cause posterior localization and found that the minimal region of the F-actin binding domain for posterior localiza-tion could, with some additional deletion at the C-terminal, localize to the anterior. Analysis of the localization and trans-location kinetics to the cell cortex of the truncated proteins suggests that the required regions for anterior/posterior lo-calization might have a preferential binding affinity to pre- existing F-actins at the rear and lateral sides of the cell or newly formed F-actins at the front of the cell, leading to dis-tinct differential sites of the cell.

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

Role of CaBud6p in the Polarized Growth of Candida albicans: Yunkyoung Song , Jeong-Yoon Kim; J. Microbiol. 2006;44(3):311-319.; DOI: https://doi.org/2381 [pii]

Abstract: Bud6p is a component of a polarisome that controls cell polarity in Saccharomyces cerevisiae. In this study, we investigated the role of the Candida albicans Bud6 protein (CaBud6p) in cell polarity and hyphal development. CaBud6p, which consists of 703 amino acids, had 37% amino-acid sequence identity with the Bud6 protein of S. cerevisiae. The homozygous knock-out of CaBUD6 resulted in several abnormal phenotypes, such as a round and enlarged cells, widened bud necks, and a random budding pattern. In hypha-inducing media, the mutant cells had markedly swollen tips and a reduced ability to switch from yeast to hypha. In addition, a yeast two-hybrid analysis showed a physical interaction between CaBud6p and CaAct1p, which suggests that CaBud6p may be involved in actin cable organization, like Bud6p in S. cerevisiae. Taken together, these results indicate that CaBud6 plays an important role in the polarized growth of C. albicans.

Isolation and Characterization of Bud6p, an Actin Interacting Protein, from Yarrowia lipolytica: Yunkyoung Song , Seon Ah Cheon , So-Yeon Lee , Ji-Sook Hwang , Jeong-Yoon Kim; J. Microbiol. 2003;41(2):121-128.

Abstract: The identification of genes involved in true hypha formation is important in the study of mechanisms underlying the morphogenetic switch in yeast. We isolated a gene responsible for the morphogenetic switch in Yarrowia lipolytica, which forms true hyphae in response to serum or N-acetylglucosamine. The isolated gene, encoding 847 amino acids, had sequence identities of 27% and 25% with the Bud6 (Aip3) proteins of Saccharomyces cerevisiae and Schizosaccharomyces pombe, respectively. Disruption of this gene, designated YlBUD6, in haploid and diploid strains significantly reduced the ability of Y. lipolytica to switch from the yeast form to the hyphal form in hypha-inducing media. It was also found that YlBud6 mutants were rounder than the wild type when grown in the yeast form. These results indicate that the YlBud6 protein is necessary for hyphal growth and cell polarity in both haploid and diploid Y. lipolytica cells.

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