Leucine-zipper transcription
regulator 1 (LZTR1) is a highly mutated
tumor suppressor gene, involved in the pathogenesis of several cancer
types and developmental disorders. In proteasomal degradation, it
acts as an adaptor protein responsible for the recognition and recruitment
of substrates to be ubiquitinated in Cullin3-RING ligase E3 (CRL3)
machinery. LZTR1 belongs to the BTB-Kelch family, a multi-domain protein
where the Kelch propeller plays as the substrate recognition region
and for which no experimental structure has been solved. Recently, large effort mutational analyses pointed to the role
of disease-associated LZTR1 mutations in the RAS/MAPK signaling pathway
and RIT1, a small Ras-related GTPase protein, has been identified
by mass spectroscopy to interact with LZTR1. Hence, a better understanding
of native structure, molecular mechanism, and substrate specificity
would help clarifying the role of LZTR1 in pathological diseases,
thus promoting advancement in the development of novel therapeutic
strategies. Here, we address the interaction model between adaptor
LZTR1 and substrate RIT1 by applying an integrated computational approach,
including molecular modeling and docking techniques. We observe that the interaction model LZTR1-RIT1 is stabilized by
an electrostatic bond network established between the two protein
surfaces, which is reminiscent of homologous ubiquitin ligases complexes.
Then, running MD simulations, we characterize differential conformational
dynamics of the multi-domain LZTR1, offering interesting implications
on the mechanistic role of specific point mutations. We identify G248R
and R283Q as damaging mutations involved in the recognition process
of the substrate RIT1 and R412C as a possible allosteric mutation
from the Kelch to the C-term BTB-domain. Our findings provide important
structural insights on targeting CRL3s for drug discovery.