Molecular Characterization of Two Mitogen-Activated Protein Kinases: p38 MAP Kinase and Ribosomal S6 Kinase From Bombyx mori (Lepidoptera: Bombycidae), and Insight Into Their Roles in Response to BmNPV Infection

Muhammad, Azharuddin; Toufeeq, Shahzad; Yu, Hai-Zhong; Wang, Jie; Zhang, Shang-Zhi; Li, Bing; Li, Zhen; Yang, Li-Ang; Hu, Pei; Ma, Yan; Xu, Jia-Ping

MAPK signaling pathways are evolutionarily conserved Ser-Thr kinases with a wide range of biological functions. MAPKs consist of three subfamilies including ERK, JNK, and p38 MAPK (Johnson and Lapadat 2002 , Roux and Blenis 2004 , Huang et al. 2009 ). The activation of MAPKs depends on phosphorylation of certain motifs found in activation loop. The p38 MAPK and S6K are important proteins of MAPK family. Evidence showed that p38 MAPK and S6K play vital role in both vertebrates and invertebrates (Roux and Blenis 2004, Fenton and Gout 2011) . However, studies on p38 and S6K MAPK proteins in silkworm had not been reported previously. Therefore, in the present study, we identified B. mori p38 and S6K proteins from iTRAQ database. The sequence analysis showed that Bmp38 and BmS6K contain S_TKc domain with 360 aa and 753 aa, respectively. Multiple sequence alignment of Bmp38 and BmS6k with other organisms (having known functions) revealed common features in all of them, e.g., activation loop and motifs. The phylogenetic analysis provided evidences that Bmp38 and BmS6K homologous are highly conserved in vertebrates and invertebrates. This phylogenetic analysis is consistent with the previous studies (Lin et al. 2017 , Yu et al. 2017c .