2 research outputs found
Sequence Determinants of the Conformational Properties of an Intrinsically Disordered Protein Prior to and upon Multisite Phosphorylation
Many cell signaling
events are coordinated by intrinsically disordered
protein regions (IDRs) that undergo multisite Serine/Threonine phosphorylation.
The conformational properties of these IDRs prior to and following
multisite phosphorylation are directly relevant to understanding their
functions. Here, we present results from biophysical studies and molecular
simulations that quantify the conformational properties of an 81-residue
IDR from the <i>S. cerevisiae</i> transcription factor
Ash1. We show that the unphosphorylated Ash1 IDR adopts coil-like
conformations that are expanded and well-solvated. This result contradicts
inferences regarding global compaction that are derived from heuristics
based on amino acid compositions for IDRs with low proline contents.
Upon phosphorylation at ten distinct sites, the global conformational
properties of pAsh1 are indistinguishable from those of unphosphorylated
Ash1. This insensitivity derives from compensatory changes to the
pattern of local and long-range intrachain contacts. We show that
the conformational properties of Ash1 and pAsh1 can be explained in
terms of the linear sequence patterning of proline and charged residues
vis-à-vis all other residues. The sequence features of the
Ash1 IDR are shared by many other IDRs that undergo multisite phosphorylation.
Accordingly, we propose that our findings might be generalizable to
other IDRs involved in cell signaling
TOI-2076 and TOI-1807: Two young, comoving planetary systems within 50 pc identified by TESS that are ideal candidates for further follow up
We report the discovery of two planetary systems around comoving stars: TOI-2076 (TIC 27491137) and TOI-1807 (TIC 180695581). TOI-2076 is a nearby (41.9 pc) multiplanetary system orbiting a young (204 ± 50 Myr), bright (K = 7.115 in TIC v8.1) start. TOI-1807 hosts a single transiting planet and is similarly nearby (42.58 pc), similarly young (180 ± 40 Myr ), and bright. Both targets exhibit significant, periodic variability due to starspots, characteristic of their young ages. Using photometric data collected by TESS we identify three transiting planets around TOI-2076 with radii of R b = 3.3 ± 0.04 R ⊕, R c = 4.4 ± 0.05 R ⊕, and R d = 4.1 ± 0.07 R ⊕. Planet TOI-2076b has a period of P b = 10.356 days. For both TOI-2076c and d, TESS observed only two transits, separated by a 2 yr interval in which no data were collected, preventing a unique period determination. A range of long periods (<17 days) are consistent with the data. We identify a short-period planet around TOI-1807 with a radius of R b = 1.8 ± 0.04 R ⊕ and a period of P b = 0.549 days. Their close proximity, and bright, cool host stars, and young ages make these planets excellent candidates for follow up. TOI-1807b is one of the best-known small (R < 2 R⊕) planets for characterization via eclipse spectroscopy and phase curves with JWST. TOI-1807b is the youngest ultra-short-period planet discovered to date, providing valuable constraints on formation timescales of short-period planets. Given the rarity of young planets, particularly in multiple-planet systems, these planets present an unprecedented opportunity to study and compare exoplanet formation, and young planet atmospheres, at a crucial transition age for formation theory