242 ISSN 0026-8933, Molecular Biology, 2019, Vol. 53, No. 2, pp. 242–248. © Pleiades Publishing, Inc., 2019. Russian Text © D.S. Karpov, E.N. Grineva, S.V. Kiseleva, E.S. Chelarskaya, D.S. Spasskaya, V.L. Karpov, 2019, published in Molekulyarnaya Biologiya, 2019, Vol. 53, No. 2, pp. 274–281. Candida glabrata Rpn4-like Protein Complements the RPN4 Deletion in Saccharomyces cerevisiae D. S. Karpov a, b, *, E. N. Grineva a , S. V. Kiseleva a , E. S. Chelarskaya a , D. S. Spasskaya a , and V. L. Karpov a a Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991 Russia b Orekhovich Institute of Biomedical Chemistry, Moscow, 119121 Russia *e-mail: aleom@yandex.ru Received September 3, 2018; revised October 6, 2018; accepted October 8, 2018 Abstract—Expression of Saccharomyces cerevisiae proteasomal genes is regulated in a coordinated manner by a system that includes the ScRpn4 transcription factor and its binding site known as PACE. Earlier we showed that, Rpn4-like proteins from the biotechnologically important yeast species Komagataella pfaffii (Pichia pas- toris), Yarrowia lipolytica, and Debaryomyces hansenii are capable of complementing the RPN4 deletion in S. cerevisiae in spite of their low structural similarity to ScRpn4. The opportunistic yeast pathogen Candida glabrata has a gene coding for a Rpn4-like protein, which has not been characterized experimentally yet. The C. glabrata ortholog ScRpn4 was expressed heterologously and found to restore the stress resistance and expression of proteasomal genes in a mutant S. cerevisiae strain with a RPN4 deletion. This complementation required the unique N-terminal region of CgRpn4. The results indicate that CgRpn4 acts as a transcriptional activator of proteasomal genes. The S. cerevisiae model can be used for further structural and functional anal- yses of CgRpn4. Keywords: Rpn4, Candida glabrata, transcription regulation, proteasomal genes, stress resistance DOI: 10.1134/S0026893319020067 INTRODUCTION The yeast Candida glabrata is an opportunistic pathogen and is often found on human mucous mem- branes as a component of the normal microflora. However, C. glabrata can cause candidiasis in certain cases, in particular, in immunocompromised patients. According to statistical estimates, C. glabrata is responsi- ble for 15‒25% of all candidiasis cases [1]. Candida gla- brata belongs to the family Saccharomycetaceae of the class Saccharomycetes and is phylogenetically closer to the baker’s yeast Saccharomyces cerevisiae than to other candidiasis agents, for example, C. albicans [2]. The virulence of C. glabrata seems to be partly related to its higher resistance to reactive oxygen spe- cies [1]. In addition, C. glabrata is resistant to azoles (e.g., fluconazole), which are fungicidal agents that impare the biosynthesis of the cell membrane compo- nent ergosterol. The Pdr1 protein is one of the key fac- tors in the resistance to drugs and oxidative stress [3]. In S. cerevisiae, expression of the gene for the Pdr1p transcription factor is regulated by Rpn4p and Pdr1p acts as a transactivator of RPN4, which is responsible for the resistance to various adverse factors, including heat shock, oxidative stress, and DNA damage-associ- ated stress [4]. In our study performed in collaboration with ger- man researchers, the Rpn4 transcription factor has first been described as a component of a system that regulates coordinated expression of the proteasomal genes [5, 6]. The 26S proteasome is an ATP-depen- dent multisubuint protease complex and is responsible for degradation of the majority of cell proteins, includ- ing damaged and misfolded proteins. A special regula- tory element known as the proteasome-associated control element (PACE, 5'-GGTGGCAAA-3') has been found in the promoters of almost all proteasome subunit genes and shown to provide a binding site for Rpn4. The S. cerevisiae Rpn4 factor (ScRpn4) regu- lates not only the proteasomal genes, but also many other genes, including those coding for components of various stress responses [7]. A bioinformatics analysis has shown that PACE-like elements and genes for ScRpn4-like proteins are restricted to yeasts of the class Saccharomycetes [2]. We have previously demonstrated that ScRpn4-like proteins of the biotechnologically important yeasts Abbreviations: PACE, proteasome-associated control element; MMS, methyl methane sulfonate; 4-NQO, 4-nitroquinoline-1- oxide; NAD, N-terminal acidic domain; CAD, C-terminal acidic domain; NTAD, N-terminal transactivation domain; N-ZnF, N-terminal zinc finger domain; C-ZnF, C-terminal zinc finger domain; QRR, glutamine-rich region. GENOMICS. TRANSCRIPTOMICS UDC 577.218