Alk1 and Alk2 are Two New Cell Cycle-Regulated Haspin-Like Proteins in Budding Yeast

Nespoli, Alessandro; Vercillo, Raffaella; Nola, L. di; Diani, Laura; Giannattasio, Michele; Plevani, Paolo; Muzi-Falconi, Marco

doi:10.4161/cc.5.13.2914

Cited by 30 publications

(37 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Despite the absence of some of the highly conserved motifs found in canonical ePKs, mammalian haspin proteins clearly have serine/threonine kinase activity (Tanaka et al 1999; Tanaka et al 2001; Dai et al 2005; Eswaran et al 2009). The even more divergent budding yeast homologs Alk1 (Ygl021wp) and Alk2 (Ybl009wp) also appear to be active kinases (Nespoli et al 2006). The N-terminal region of haspin proteins is poorly conserved, but some general features, such as a preponderance of serine and arginine/lysine residues, are shared between different species (Higgins 2003).…”

Section: Haspin Homologues and Structurementioning

confidence: 99%

“…Although plants possess haspin homologues, it remains to be determined if they are required for mitotic H3T3ph in these species. Phosphorylation of histones by recombinant budding yeast haspin homologues Alk1 and Alk2 was not observed in vitro (Nespoli et al 2006), and as yet there are no reports of H3T3ph in fungal cells. Although these results are not definitive, they hint at the existence of alternative substrates for haspin in yeasts and other organisms.…”

Section: Haspin Phosphorylates Histone H3t3mentioning

confidence: 99%

See 1 more Smart Citation

Haspin: a newly discovered regulator of mitotic chromosome behavior

Higgins

2009

Chromosoma

View full text Add to dashboard Cite

The haspins are divergent members of the eukaryotic protein kinase family that are conserved in many eukaryotic lineages including animals, fungi, and plants. Recently-solved crystal structures confirm that the kinase domain of human haspin has unusual structural features that stabilize a catalytically active conformation and create a distinctive substrate binding site. Haspin localizes predominantly to chromosomes and phosphorylates histone H3 at threonine-3 during mitosis, particularly at inner centromeres. This suggests that haspin directly regulates chromosome behavior by modifying histones, although it is likely that additional substrates will be identified in the future. Depletion of haspin by RNA interference in human cell lines causes premature loss of centromeric cohesin from chromosomes in mitosis and failure of metaphase chromosome alignment, leading to activation of the spindle assembly checkpoint and mitotic arrest. Haspin overexpression stabilizes chromosome arm cohesion. Haspin, therefore, appears to be required for protection of cohesion at mitotic centromeres. Saccharomyces cerevisiae homologues of haspin, Alk1 and Alk2, are also implicated in regulation of mitosis. In mammals, haspin is expressed at high levels in the testis, particularly in round spermatids, so it seems likely that haspin has an additional role in post-meiotic spermatogenesis. Haspin is currently the subject of a number of drug discovery efforts, and the future use of haspin inhibitors should provide new insight into the cellular functions of these kinases and help determine the utility of, for example, targeting haspin for cancer therapy.

show abstract

Section: Haspin Homologues and Structurementioning

confidence: 99%

Section: Haspin Phosphorylates Histone H3t3mentioning

confidence: 99%

Haspin: a newly discovered regulator of mitotic chromosome behavior

Higgins

2009

Chromosoma

View full text Add to dashboard Cite

show abstract

“…Haspin autophosphorylates in vitro (4,6,8) and phosphorylates its only currently known substrate, histone H3, at threonine-3 (H3T3ph) both in vitro and in cells (6). H3T3 phosphorylation occurs specifically during mitosis and is particularly prominent at inner centromere regions (6,7,9).…”

mentioning

confidence: 99%

Structure and functional characterization of the atypical human kinase haspin

Eswaran

Patnaik

Filippakopoulos

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

155

167

View full text Add to dashboard Cite

The protein kinase haspin/Gsg2 plays an important role in mitosis, where it specifically phosphorylates Thr-3 in histone H3 (H3T3). Its protein sequence is only weakly homologous to other protein kinases and lacks the highly conserved motifs normally required for kinase activity. Here we report structures of human haspin in complex with ATP and the inhibitor iodotubercidin. These structures reveal a constitutively active kinase conformation, stabilized by haspin-specific inserts. Haspin also has a highly atypical activation segment well adapted for specific recognition of the basic histone tail. Despite the lack of a DFG motif, ATP binding to haspin is similar to that in classical kinases; however, the ATP ␥-phosphate forms hydrogen bonds with the conserved catalytic loop residues Asp-649 and His-651, and a His651Ala haspin mutant is inactive, suggesting a direct role for the catalytic loop in ATP recognition. Enzyme kinetic data show that haspin phosphorylates substrate peptides through a rapid equilibrium random mechanism. A detailed analysis of histone modifications in the neighborhood of H3T3 reveals that increasing methylation at Lys-4 (H3K4) strongly decreases substrate recognition, suggesting a key role of H3K4 methylation in the regulation of haspin activity.ATP binding ͉ histone modification ͉ phosphorylation mechanism ͉ germ cell-specific gene 2 (Gsg2) ͉ mitosis E ukaryotic protein kinases (ePKs) constitute a large group of enzymes that regulate a vast diversity of cellular processes. Kinase activity depends on a number of highly conserved sequence motifs required for ATP/Mg 2ϩ binding and catalysis. About 10% of human ePKs lack one or more essential catalytic motifs and have been initially classified as inactive pseudokinases (1). However, a number of such proteins are active kinases, including haspin [haploid germ cell-specific nuclear protein kinase, encoded by Germ cell-specific gene 2 (Gsg2)]. Haspin lacks both the conserved ATP/Mg 2ϩ binding motif Asp-Phe-Gly (DFG), which is replaced by Asp-Tyr-Thr (DYT), and the Ala-Pro-Glu (APE) motif usually found at the C terminus of the activation segment (2). In addition, haspin shares only weak sequence homology with ePKs and contains a highly divergent kinase domain with several unique inserts (2, 3). Haspin mRNA is abundant in testis and also present in somatic cells (4, 5), and orthologues are found throughout eukaryotic phyla (2). Ectopically expressed haspin localizes to the nucleus in interphase and to the chromosomes in mitosis (4, 6), while depletion of haspin leads to premature chromatid separation, failure of chromosome alignment, and a block in mitosis in a prometaphase-like state (6, 7).Haspin autophosphorylates in vitro (4, 6, 8) and phosphorylates its only currently known substrate, histone H3, at threonine-3 (H3T3ph) both in vitro and in cells (6). H3T3 phosphorylation occurs specifically during mitosis and is particularly prominent at inner centromere regions (6, 7, 9). Recently, H3T3ph has been suggested to relieve an inhibitory effect of ...

show abstract

“…Thus, it is conceivable that Npr1 might differentially regulate routes for influx or efflux of particular substances and thereby enable chemical resistance. We also found evidence for functional divergence of the paralogs Alk1 and Alk2 (haspin-like kinases) through the rank plot analysis (Fig 4a) 76 . Alk1 and Alk2 are highly regulated during the cell cycle 76 .…”

Section: Resultsmentioning

confidence: 67%

“…We also found evidence for functional divergence of the paralogs Alk1 and Alk2 (haspin-like kinases) through the rank plot analysis (Fig 4a) 76 . Alk1 and Alk2 are highly regulated during the cell cycle 76 . Alk2 is required for growth in the presence of 15 chemical compounds, whereas Alk1 is connected to a single substance.…”

Section: Resultsmentioning

confidence: 67%

Robustness and evolvability in natural chemical resistance: identification of novel systems properties, biochemical mechanisms and regulatory interactions

et al. 2010

View full text Add to dashboard Cite

A vast amount of data on the natural resistance of Saccharomyces cerevisiae to a diverse array of chemicals has been generated over the past decade (chemical genetics). We endeavored to use this data to better characterize the “systems” level properties of this phenomenon. By collating data from over 30 different genome-scale studies on growth of gene deletion mutants in presence of diverse chemicals, we assembled the largest currently available gene-chemical network. We also derived a second gene-gene network that links genes with significantly overlapping chemical-genetic profiles. We analyzed properties of these networks and investigated their significance by overlaying various sources of information, such as presence of TATA boxes in their promoters (which typically correlate with transcriptional noise), association with TFIID or SAGA, and propensity to function as phenotypic capacitors. We further combined these networks with ubiquitin and protein kinase-substrate networks to understand chemical tolerance in the context of major post-translational regulatory processes. Hubs in the gene-chemical network (multidrug resistance genes) are notably enriched for phenotypic capacitors (buffers against phenotypic variation), suggesting the generality of these players in buffering mechanistically unrelated deleterious forces impinging on the cell. More strikingly, analysis of the gene-gene network derived from the gene-chemical network uncovered another set of genes that appear to function in providing chemical tolerance in a cooperative manner. These appear to be enriched in lineage-specific and rapidly diverging members that also show a corresponding tendency for SAGA-dependent regulation, evolutionary divergence and noisy expression patterns. This set represents a previously underappreciated component of the chemical response that enables cells to explore alternative survival strategies. Thus, systems robustness and evolvability are simultaneously active as general forces in tolerating environmental variation. We also recover the actual genes involved in the above-discussed network properties and predict the biochemistry of their products. Certain key components of the ubiquitin system (e.g. Rcy1, Wss1 and Ubp16), peroxisome recycling (e.g. Irs4) and phosphorylation cascades (e.g. NPR1, MCK1 and HOG) are major participants and regulators of chemical resistance. We also show that a major subnetwork boosting mitochondrial protein synthesis is important for exploration of alternative survival strategies under chemical stress. Further, we find evidence that cellular exploration of survival strategies under chemical stress and secondary metabolism draw from a common pool of biochemical players (e.g. acetyltransferases and a novel NTN hydrolase).

show abstract

Alk1 and Alk2 are Two New Cell Cycle-Regulated Haspin-Like Proteins in Budding Yeast

Cited by 30 publications

References 31 publications

Haspin: a newly discovered regulator of mitotic chromosome behavior

Haspin: a newly discovered regulator of mitotic chromosome behavior

Structure and functional characterization of the atypical human kinase haspin

Robustness and evolvability in natural chemical resistance: identification of novel systems properties, biochemical mechanisms and regulatory interactions

Contact Info

Product

Resources

About