The metastasis suppressor KISS1 is an intrinsically disordered protein slightly more extended than a random coil

Abstract

The metastasis suppressor KISS1 is reported to be involved in the progression of several solid neoplasias, making it a promising molecular target for controlling their metastasis. The KISS1 sequence contains an N-terminal secretion signal and several dibasic sequences that are proposed to be the proteolytic cleavage sites. We present the first structural characterization of KISS1 by circular dichroism, multi-angle light scattering, small angle X-Ray scattering and NMR spectroscopy. An analysis of the KISS1 backbone NMR chemical shifts does not reveal any preferential conformation and deviation from a random coil ensemble. The backbone 15N transverse relaxation times indicate a mildly reduced mobility for two regions that are rich in bulky residues. The small angle X-ray scattering curve of KISS1 is likewise consistent with a predominantly random coil ensemble, although an ensemble optimization analysis indicates some preference for more extended conformations possibly due to positive charge repulsion between the abundant basic residues. Our results support the hypothesis that KISS1 mostly samples a random coil conformational space, which is consistent with its high susceptibility to proteolysis and the generation of Kisspeptin fragments.

Double Monoubiquitination Modifies the Molecular Recognition Properties of p15PAF Promoting Binding to the Reader Module of Dnmt1

“…NMR is then the method of choice for conformational analysis, together with SAXS, which has the capacity to report on the threedimensional space sampled by disordered states and, thus, complements the local information provided by NMR. 26,36 The interest in IDPs has recently increased because of their involvement in the formation of membraneless organelles via protein phase separation. 37 Solutions of p15 or dmUbp15, however, do not show phase separation (at least up to 20 g/L at 25 °C), and our SEC-MALS data demonstrate that both are monomeric.…”

The influence of random-coil chemical shifts on the assessment of structural propensities in folded proteins and IDPs

“…84 This requires authors to lter the data in some manner that decomposes the measured CSs into RCCSs and the different contributions of all the experimental conditions, the local sequence and, most importantly, residual structure. 63,66,85,86 Loop regions, denatured proteins and even some peptides have been shown to not be completely disordered. [87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102] In the light of the above, in Table 1 we summarize the works that have been carried out with the aim of calibrating RCCSs.…”

“…84 This requires authors to filter the data in some manner that decomposes the measured CSs into RCCSs and the different contributions of all the experimental conditions, the local sequence and, most importantly, residual structure. 63,66,85,86 Loop regions, denatured proteins and even some peptides have been shown to not be completely disordered. 87–102…”