A subdomain of MEKK1 that is critical for binding to MKK4

Tu, Zheng; Mooney, Sharon M; Lee, Frank S.

doi:10.1016/s0898-6568(02)00056-6

Cited by 14 publications

(20 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The critical participation of subdomain X in signaling of MAPK has been described recently (84,85). Selected alanine mutations within subdomain X of the MAPK kinase kinase (MAP3K) MEKK1, especially of two hydrophobic residues (F1443A and I1445A), diminished binding and activation of its downstream target MAPK kinase (MAP2K) MKK4 and activation of other downstream kinases (MKK7, IKK, and MEK1) (85).…”

Section: Discussionmentioning

confidence: 99%

“…Selected alanine mutations within subdomain X of the MAPK kinase kinase (MAP3K) MEKK1, especially of two hydrophobic residues (F1443A and I1445A), diminished binding and activation of its downstream target MAPK kinase (MAP2K) MKK4 and activation of other downstream kinases (MKK7, IKK, and MEK1) (85). Furthermore, hydrophobic residues of subdomain X were also required for proper MEKK2-dependent activation of c-Jun NH 2 -terminal kinase (JNK) and ERK5 pathways (84).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Homo-oligomerization and Activation of AMP-activated Protein Kinase Are Mediated by the Kinase Domain αG-Helix

Scholz

Suter

Weimann

et al. 2009

Journal of Biological Chemistry

View full text Add to dashboard Cite

AMP-activated protein kinase (AMPK) is a heterotrimeric complex playing a crucial role in maintaining cellular energy homeostasis. Recently, homodimerization of mammalian AMPK and yeast ortholog SNF1 was shown by us and others. In SNF1, it involved specific hydrophobic residues in the kinase domain ␣G-helix. Mutation of the corresponding AMPK ␣-subunit residues (Val-219 and Phe-223) to glutamate reduced the tendency of the kinase to form higher order homo-oligomers, as was determined by the following three independent techniques in vitro: (i) small angle x-ray scattering, (ii) surface plasmon resonance spectroscopy, and (iii) two-dimensional blue native/SDS-PAGE. Recombinant protein as well as AMPK in cell lysates of primary cells revealed distinct complexes of various sizes. In particular, the assembly of very high molecular mass complexes was dependent on both the ␣G-helix-mediated hydrophobic interactions and kinase activation. In vitro and when overexpressed in double knock-out (␣1) mouse embryonic fibroblast cells, activation of mutant AMPK was impaired, indicating a critical role of the ␣G-helix residues for AMPK activation via its upstream kinases. Also inactivation by protein phosphatase 2C␣ was affected in mutant AMPK. Importantly, activation of mutant AMPK by LKB1 was restored by exchanging the corresponding and conserved hydrophobic ␣G-helix residues of LKB1 (Ile-260 and Phe-264) to positively charged amino acids. These mutations functionally rescued LKB1-dependent activation of mutant AMPK in vitro and in cell culture. Our data suggest a physiological role for the hydrophobic ␣G-helix residues in homo-oligomerization of heterotrimers and cellular interactions, in particular with upstream kinases, indicating an additional level of AMPK regulation.The maintenance of energy homeostasis is a basic requirement of all living organisms. The AMP-activated protein kinase (AMPK) 2 is crucially involved in this essential process by playing a central role in sensing and regulating energy metabolism on the cellular and whole body level (1-6). AMPK is also participating in several signaling pathways associated with cancer and metabolic diseases, like type 2 diabetes mellitus, obesity, and other metabolic disorders (7-9).Mammalian AMPK belongs to a highly conserved family of serine/threonine protein kinases with homologs found in all eukaryotic organisms examined (1, 3, 10). Its heterotrimeric structure includes a catalytic ␣-subunit and regulatory ␤-and ␥-subunits. These subunits exist in different isoforms (␣1, ␣2, ␤1, ␤2, ␥1, ␥2, and ␥3) and splice variants (for ␥2 and ␥3) and can thus assemble to a broad variety of heterotrimeric isoform combinations. The ␣-and ␤-subunits possess multiple autophosphorylation sites, which have been implicated in regulation of subcellular localization and kinase activation (11-15). The most critical step of AMPK activation, however, is phosphorylation of Thr-172 within the activation segment of the ␣-subunit kinase domain. At least two AMPK upstream kinases (AMPKKs) have been i...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Homo-oligomerization and Activation of AMP-activated Protein Kinase Are Mediated by the Kinase Domain αG-Helix

Scholz

Suter

Weimann

et al. 2009

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…A similar though not identical set of mutations also displays effects on MEKK2 (28). A major limitation of the mutations in those studies, however, is that they compromised the ability of MEKK1 to not only activate MKK4, but also MKK7, IKK, and MEK1 (27). Thus, these mutants do not provide an explanation for how MEKK1 can distinguish between substrates, and even raise the possibility that some of these mutants might be structurally compromised.…”

Section: Mitogen-activated Protein Kinase (Mapk)mentioning

confidence: 95%

“…Thus, even if this docking interaction were to play a role in the MEKK1/MKK4 interaction, additional contacts must exist. In this regard, we have reported that select amino acid mutations of subdomain X of MEKK1 abolish its ability to bind to and activate MKK4 (27). A similar though not identical set of mutations also displays effects on MEKK2 (28).…”

Section: Mitogen-activated Protein Kinase (Mapk)mentioning

confidence: 98%

Subdomain VIII Is a Specificity-determining Region in MEKK1

Lee

2003

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

MAPK/ERK kinase kinase 1 (MEKK1) is a mitogenactivated protein kinase kinase kinase (MAP3K) of the stress-induced JNK pathway. Once activated, MEKK1 phosphorylates the MAP2K MKK4, which in turn phosphorylates JNK. MEKK1 also has the capacity to activate IKK, the central protein kinase of the NF-B pathway. The molecular determinants responsible for the ability of MEKK1 to recognize specific substrates are poorly understood. We report here that select point mutations in subdomain VIII of the protein kinase domain of MEKK1 (MEKK1⌬) differentially affect its ability to activate MKK4 and IKK, and consequently AP1 and NF-B reporter genes. Moreover, binding of MKK4 to MEKK1⌬ protects the latter from cleavage at an engineered protease target site in subdomain VIII. Collectively these results provide evidence that subdomain VIII of MEKK1 is involved not only in binding to, but also in discrimination of, protein substrates.

show abstract

“…For example, MKK4 binds to the kinase domain of MEKK1 and mutations that block this interaction lead to reduced MKK4 activation (25,26). Similarly, the MLK family member DLK associates with MKK7, but not MKK4, and this correlates with the ability of DLK to preferentially activate MKK7 (27).…”

mentioning

confidence: 99%