TY - JOUR

T1 - Insight into Calcium-Binding Motifs of Intrinsically Disordered Proteins

AU - Newcombe, Estella A.

AU - Fernandes, Catarina B.

AU - Lundsgaard, Jeppe E.

AU - Brakti, Inna

AU - Lindorff-Larsen, Kresten

AU - Langkilde, Annette E.

AU - Skriver, Karen

AU - Kragelund, Birthe B.

N1 - This article belongs to the Special Issue Protein Intrinsic Disorder: Role in Signaling, Regulation and Membrane-Less Organelle Formation

PY - 2021

Y1 - 2021

N2 - Motifs within proteins help us categorize their functions. Intrinsically disordered proteins (IDPs) are rich in short linear motifs, conferring them many different roles. IDPs are also frequently highly charged and, therefore, likely to interact with ions. Canonical calcium-binding motifs, such as the EF-hand, often rely on the formation of stabilizing flanking helices, which are a key characteristic of folded proteins, but are absent in IDPs. In this study, we probe the existence of a calcium-binding motif relevant to IDPs. Upon screening several carefully selected IDPs using NMR spectroscopy supplemented with affinity quantification by colorimetric assays, we found calcium-binding motifs in IDPs which could be categorized into at least two groups—an Excalibur-like motif, sequentially similar to the EF-hand loop, and a condensed-charge motif carrying repetitive negative charges. The motifs show an affinity for calcium typically in the ~100 µM range relevant to regulatory functions and, while calcium binding to the condensed-charge motif had little effect on the overall compaction of the IDP chain, calcium binding to Excalibur-like motifs resulted in changes in compaction. Thus, calcium binding to IDPs may serve various structural and functional roles that have previously been underreported.

AB - Motifs within proteins help us categorize their functions. Intrinsically disordered proteins (IDPs) are rich in short linear motifs, conferring them many different roles. IDPs are also frequently highly charged and, therefore, likely to interact with ions. Canonical calcium-binding motifs, such as the EF-hand, often rely on the formation of stabilizing flanking helices, which are a key characteristic of folded proteins, but are absent in IDPs. In this study, we probe the existence of a calcium-binding motif relevant to IDPs. Upon screening several carefully selected IDPs using NMR spectroscopy supplemented with affinity quantification by colorimetric assays, we found calcium-binding motifs in IDPs which could be categorized into at least two groups—an Excalibur-like motif, sequentially similar to the EF-hand loop, and a condensed-charge motif carrying repetitive negative charges. The motifs show an affinity for calcium typically in the ~100 µM range relevant to regulatory functions and, while calcium binding to the condensed-charge motif had little effect on the overall compaction of the IDP chain, calcium binding to Excalibur-like motifs resulted in changes in compaction. Thus, calcium binding to IDPs may serve various structural and functional roles that have previously been underreported.

KW - Calcium

KW - IDP

KW - Intrinsically disordered proteins

KW - Motifs

KW - NMR

KW - SLiM

U2 - 10.3390/biom11081173

DO - 10.3390/biom11081173

M3 - Journal article

C2 - 34439840

AN - SCOPUS:85112617448

VL - 11

JO - Biomolecules

JF - Biomolecules

SN - 2218-273X

IS - 8

M1 - 1173

ER -