NDD1, a High-Dosage Suppressor of cdc28-1N, Is Essential for Expression of a Subset of Late-S-Phase-Specific Genes in Saccharomyces cerevisiae

Abstract

cdc28-1N mutants progress through the G1 and S phases normally at the restrictive temperature but fail to undergo nuclear division. We have isolated a gene, NDD1, which at a high dosage suppresses the nuclear-division defect of cdc28-1N. NDD1 (nuclear division defective) is an essential gene. Its expression during the cell cycle is tightly regulated such that NDD1 RNA is most abundant during the S phase. Cells lacking the NDD1 gene arrest with an elongated bud, a short mitotic spindle, 2N DNA content, and an undivided nucleus, suggesting that its function is required for some aspect of nuclear division. We show that overexpression of Ndd1 results in the upregulation of both CLB1 and CLB2 transcription, suggesting that the suppression of cdc28-1N by NDD1 may be due to an accumulation of these cyclins. Overproduction of Ndd1 also enhances the expression of SWI5, whose transcription, like that of CLB1 and CLB2, is activated in the late S phase. Ndd1 is essential for the expression of CLB1, CLB2, and SWI5, since none of these genes are transcribed in its absence. Both CLB2 expression and its upregulation by NDD1 are mediated by a 240-bp promoter sequence that contains four MCM1-binding sites. However, Ndd1 does not appear to be a component of any of the protein complexes assembled on this DNA fragment, as indicated by gel mobility shift assays. Instead, overexpression of NDD1 prevents the formation of one of the complexes whose appearance correlates with the termination of CLB2 expression in G1. The inability of GAL1 promoter-driven CLB2 to suppress the lethality of NDD1 null mutant suggests that, in addition to CLB1 and CLB2, NDD1 may also be required for the transcription of other genes whose functions are necessary for G2/M transition.

Discovering gene association networks by multi-objective evolutionary quantitative association rules

“…The association CLB1-CLB2 is in agreement with CLB2 and CLB1 being expressed simultaneously in G2 [63]. The rules CLB2-SWI5, CLB1-SWI5 are in agreement with the literature: transcription of SWI5 and CLB1 is G 2 /M specific and activated in late S phase; the expression pattern of SWI5 is similar to that of CLB1 and CLB2 and the peak of mRNA concentration of SWI5 is in G2 [64] and [65]. The association CLN2-CLN1 is consistent with the knowledge that CLN2 and CLN1 have their transcription maximum in G1 [9] whereas CDC20 is transcribed in late S/G 2 phase.…”

Bck2 is a phase-independent activator of cell cycle-regulated genes in yeast

“…For instance, this is likely the case for the M/G 1 transcription factors Swi5 and Ace2, which both peaked at 60 and 80 min in the Cln3 and Bck2 time series, respectively. Transcriptional induction of these regulators depends on, among other factors, Ndd1, Clb2 and Cdc5, [60][61][62][63] all of which were also upregulated. In order to consider the primary effects of Cln3 and Bck2 on gene expression in the G 1 block/release experiment, in the following analyses we used only the earliest induced genes, defined as being upregulated over 1.4-fold in the 20-min and 40-min point in the Cln3 and Bck2 series, respectively.…”

Degradation of Ndd1 by APC/CCdh1 generates a feed forward loop that times mitotic protein accumulation

“…2) but Ndd1 counteracts APC/C Cdh1 activity. Interestingly, the inactivation of Ndd1 leads to a cell cycle arrest with elongated buds and replicated DNA 27 , which is strikingly similar to the phenotype caused by Cdh1 m11 expression.…”

“…Indeed, Fig. 4d shows that induced expression of Ndd1 rescues the expression of Clb2 and Cdc20, known to be activated by Ndd1 transcriptionally 27,37 and degraded by the APC/C Cdh1 (ref. 38), even in the presence of constitutively active Cdh1 m11 .…”

“…Ndd1 mediates the transcription of mitotic regulators like Clb2 (ref. 27) and Cdc5 (ref. 35), which are degraded by the APC/C Cdh1 .…”