Abstract
LAMMER kinase plays pivotal roles in various physiological processes in eukaryotes; however, its function in filamentous fungi is not known. We performed molecular studies on the function of the Aspergillus nidulans LAMMER kinase, LkhA, and report its involvement in multiple developmental processes. The gene for LkhA was highly expressed during reproductive organ development, such as that of conidiophores and cleistothecia. During vegetative growth, the patterns of germ tube emergence and hyphal polarity were changed and septation was increased by lkhA deletion. Northern analyses showed that lkhA regulated the transcription of brlA, csnD, and ppoA, which supported the detrimental effect of lkhA-deletion on asexual and sexual differentiation. LkhA also affected expression of cyclin-dependent kinase NimXcdc2, a multiple cell cycle regulator, and StuA, an APSES family of fungal transcription factors that play pivotal roles in multiple differentiation processes. Here, for the first time, we present molecular evidence showing that LAMMER kinase is involved in A. nidulans development by modulating the expression of key regulators of developmental processes.
Highlights
The LAMMER kinases are found throughout eukaryotes and are known to conserve the motif ‘‘EHLAMMERILG’’, which is important for the kinase activity and substrate recognition [1,2]
To understand the functions of LAMMER kinase in Aspergillus nidulans, a homologous gene was identified by searching through the A. nidulans genome database for its conserved motif, EHLAMMERILG, and we named this LkhA (LAMMER Kinase Homolog, Accession No XM653500, AN0988)
These analyses indicated that LkhA belongs to the family of LAMMER kinases
Summary
The LAMMER kinases are found throughout eukaryotes and are known to conserve the motif ‘‘EHLAMMERILG’’, which is important for the kinase activity and substrate recognition [1,2] These kinases possess dual-specificity kinase activity, resulting in the phosphorylation of serine, threonine, and tyrosine residues [1,3,4,5,6]. The Schizosaccharomyces pombe LAMMER kinase, Lkh, acts in filamentous adhesion growth on agar surfaces and negative regulation for a divalent cation-dependent asexual flocculation [10]. It phosphorylates an mRNA binding factor, Csx, which is related to both oxidative stress response and sexual differentiation, and Tup transcription factors, which regulate expression of the glucoserepressible genes [11,12,13]. Recent results indicate the involvement of Lkh in pre-mRNA splicing and cell wall assembly of the fission yeast [14,15]
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