Reduction of ribosome level triggers flocculation of fission yeast cells.
Deletion of ribosomal protein L32 genes resulted in a nonsexual flocculation of fission yeast. Nonsexual flocculation also occurred when two other ribosomal protein genes, rpl21-2 and rpl9-2, were deleted. However, deletion of two nonribosomal protein genes, mpg and fbp, did not cause flocculation. Overall transcript levels of rpl32 in rpl32-1Δ and rpl32-2Δ cells were reduced by 35.9% and 46.9%, respectively, and overall ribosome levels in rpl32-1Δ and rpl32-2Δ cells dropped 31.1% and 27.8%, respectively, compared to wild-type cells. Interestingly, ribosome protein expression levels and ribosome levels were also reduced greatly in sexually flocculating diploid YHL6381/WT (h⁺/h⁻) cells compared to a mixture of YHL6381 (h⁺) and WT (h⁻) nonflocculating haploid cells. Transcriptome analysis indicated that the reduction of ribosomal levels in sexual flocculating cells was caused by more-extensive suppression of ribosomal biosynthesis gene expression, while the reduction of ribosomal levels caused by deleting ribosomal protein genes in nonsexual flocculating cells was due to an imbalance between ribosomal proteins. We propose that once the reduction of ribosomal levels is below a certain threshold value, flocculation is triggered.
Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing, People's Republic of China.
Rongpeng
R
Li
Xuesong
X
Li
Lei
L
Sun
Feifei
F
Chen
Zhenxing
Z
Liu
Yuyu
Y
Gu
Xiaoyan
X
Gong
Zhonghua
Z
Liu
Hua
H
Wei
Ying
Y
Huang
Sheng
S
Yuan
D005427:Flocculation; D006597:Fructose-Bisphosphatase / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D006238:Haploidy; D056265:Microbial Interactions / Q000235:genetics*; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism
D012333:RNA, Messenger; C510544:RPL32-2 protein, S pombe; D012269:Ribosomal Proteins; D029702:Schizosaccharomyces pombe Proteins; C049650:ribosomal protein L9; C060232:ribosomal protein L21; D009713:Nucleotidyltransferases; C026917:mannose 1-phosphate guanylyltransferase; D006597:Fructose-Bisphosphatase