Structural and functional characterization of the protein kinase Mps1 in Arabidopsis thaliana.
In eukaryotes, protein kinases catalyze the transfer of a gamma-phosphate from ATP (or GTP) to specific amino acids in protein targets. In plants, protein kinases have been shown to participate in signaling cascades driving responses to environmental stimuli and developmental processes. Plant meristems are undifferentiated tissues that provide the major source of cells that will form organs throughout development. However, non-dividing specialized cells can also dedifferentiate and re-initiate cell division if exposed to appropriate conditions. Mps1 (Monopolar spindle) is a dual-specificity protein kinase that plays a critical role in monitoring the accuracy of chromosome segregation in the mitotic checkpoint mechanism. Although Mps1 functions have been clearly demonstrated in animals and fungi, its role in plants is so far unclear. Here, using structural and biochemical analyses here we show that Mps1 has highly similar homologs in many plant genomes across distinct lineages (e.g. AtMps1 in Arabidopsis thaliana). Several structural features (i.e. catalytic site, DFG motif and threonine triad) are clearly conserved in plant Mps1 kinases. Structural and sequence analysis also suggest that AtMps1 interact with other cell cycle proteins, such as Mad2 and MAPK1. By using a very specific Mps1 inhibitor (SP600125) we show that compromised AtMps1 activity hampers the development of A. thaliana seedlings in a dose-dependent manner, especially in secondary roots. Moreover, concomitant administration of the auxin IAA neutralizes the AtMps1 inhibition phenotype, allowing secondary root development. These observations let us to hypothesize that AtMps1 might be a downstream regulator of IAA signaling in the formation of secondary roots. Our results indicate that Mps1 might be a universal component of the Spindle Assembly Checkpoint machinery across very distant lineages of eukaryotes.
Laboratório de Biotecnologia Vegetal, Núcleo em Ecologia e Desenvolvimento Sócio-ambiental de Macaé, Universidade Federal do Rio de Janeiro, Macaé, Rio de Janeiro, Brazil.
Eduardo Alves Gamosa
EA
de Oliveira
Nelilma Correia
NC
Romeiro
Elane da Silva
Eda S
Ribeiro
Claudete
C
Santa-Catarina
Antônia Elenir Amâncio
AE
Oliveira
Vanildo
V
Silveira
Gonçalo Apolinário
GA
de Souza Filho
Thiago Motta
TM
Venancio
Marco Antônio Lopes
MA
Cruz
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry*; D002384:Catalysis; D018797:Cell Cycle Proteins / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D018517:Plant Roots / Q000378:metabolism; D011494:Protein Kinases / Q000737:chemistry*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D011505:Protein-Tyrosine Kinases / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; C580860:Mps1 protein, Arabidopsis; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C075840:TTK protein, human