FlexAppeal molecular dynamics, prepared and analysed

FlexAppeal

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ABL1 kinase, inactive start with imatinib

Simulated
50ns
Frames
500
Final RMSD
1.75Å

mean of the last 10% of frames

Radius of gyration
19.69Å

trajectory mean

Hydrogen bonds
425

occupancy > 10%

Helix content
39%

trajectory mean

Throughput
211ns/day

OpenCL

Wall time
5.7h
Equilibrated
1ns

restrained, before production

Settles after
0.0ns

stationary from the first frame, by pymbar.detect_equilibration

Force field
amber14-all.xml
Platform
OpenCL
Structure
2HYY.pdb

Structure

The decimated trajectory, 500 frames of 4323 atoms. Press play, or scrub the frame slider: the plots below highlight the frame you are on.

Two-dimensional structure of the ligand, each atom shaded by how far it moved over the scored window
mobility Each atom is shaded by how far it moved over the scored window, in six bands of half an angstrom: deep indigo for an atom that held still, through to amber for 3.0 angstrom and over. The bands are the same on every diagram, so a still ligand reads as still rather than being stretched to fill the scale.
0.0 ns

Loading the structure…

The binding site

A 99.0/100
Pose 100.0 30%
Occupancy 100.0 20%
Interactions 100.0 20%
Energy -60.9 kcal/mol ± 3.5 100.0 15%
Convergence 93.6 10%
Conformation 92.9 5%

Ligand pose

What this shows

Two fits of the same ligand. Against the pocket, the curve is the ligand moving in a receptor held still; against itself, it is the ligand changing shape. The shaded head is the equilibration that was measured and not scored.

Centroid drift

What this shows

Displacement of the ligand centroid from where it started. The dotted line at 5 Å is the drift beyond which DeepFlex caps a grade.

Pocket occupancy

What this shows

Receptor residues in contact with the ligand. The dotted line is a quarter of the contacts present at the start, which is the threshold for counting a frame as still bound.

Interaction occupancy

What this shows

Which contacts carried the pose, and for how much of the scored window. Typed from heavy-atom geometry, so these are polar, ionic and hydrophobic contacts rather than a full interaction fingerprint.

Contact barcode

What this shows

When each contact was present, busiest first. Gaps are the contact breaking and reforming.

Pose clusters

What this shows

How the scored window divides into distinct poses. One tall bar near zero is a ligand that held its pose.

Ligand strain

What this shows

MMFF94 strain in excess of the starting pose, never the absolute energy. Below zero means the ligand relaxed out of the pose it started in, which is a good outcome rather than a neutral one.

Ligand torsions

What this shows

Each rotatable torsion over the run. Flat traces are a rigid ligand; a trace jumping between bands is a rotamer flip.

Ligand atom fluctuation

What this shows

Which part of the ligand moves, about its own mean position.

Receptor flexibility

What this shows

Per-residue backbone fluctuation, with the binding-site residues marked. A mobile pocket makes every pose measurement noisier.

Frame-to-frame RMSD

What this shows

Every frame against every other. Blocks along the diagonal are distinct states; a uniform field is a run that stayed in one.

Residue cross-correlation

What this shows

Which parts of the receptor move together. Blue is correlated, red is anticorrelated.

MM/GBSA, term by term

What this shows

Where the binding energy comes from. The bars are the difference block, complex minus receptor minus ligand, which is the only part of an MM/GBSA calculation that is a binding quantity. Error bars are the standard deviation over the sampled frames, not the standard error. igb=2, single trajectory, no entropy term: good for ranking ligands against each other, not an affinity.

The whole system

RMSD

What this shows

How far the structure has moved from its reference. A plateau means the trajectory has settled; a steady climb means it has not.

Radius of gyration

What this shows

Global compactness. A rise suggests unfolding or expansion.

Per-residue fluctuation

What this shows

Which parts of the molecule move. Peaks are usually loops and termini.

Solvent exposure

What this shows

Total solvent-accessible surface area over time.

Secondary structure content

What this shows

Helix and sheet content over the trajectory.

Secondary structure timeline

What this shows

Per-residue assignment at every frame. Vertical stripes are transient melting; horizontal bands are stable elements.

Contact map

What this shows

How often each residue pair is in contact across the whole trajectory.

Essential dynamics

What this shows

The two dominant collective motions, with each frame coloured by time. Distinct clouds mean distinct conformational states.

Conformational clusters

What this shows

Representative states found by RMSD clustering.

Ligand pose stability

What this shows

How far the ligand moves within the binding site, with the protein held fixed. A flat trace means the pose held; a jump means it moved or left.

Protein-ligand contacts

What this shows

Which residues the ligand touches, and for what fraction of the run.

Convergence

What this shows

Each measure on its own axis. Energies, temperature and density differ by orders of magnitude, so sharing a plot between any two of them would make their alignment arbitrary and any apparent correlation fictional.

Reference states

The same trajectory measured against the experimental structures of this same protein in both of its known states, motif by motif, rather than against itself. Every threshold below is either published and cited or refitted and reported as refitted, and every reference structure was resolved from KLIFS or GPCRdb at run time.

State score over time

What this shows

The whole protein as one number, against the experimental active and inactive structures of this same protein: +1 is the active references, -1 the inactive ones. The thin line is per frame and the bold one is smoothed over 2.0 ns. The shaded bands start at s = ±0.2, which is where a label is decided; inside them the protein reads as intermediate.

Motif timelines

What this shows

Each structural motif scored separately, in the colours section 6.1 fixes for them. The whole-protein score above is these weighted by residue count, which is why a small motif moving a long way can leave it almost unchanged. Motifs of unequal discriminating power carry equal residue weight, so read this panel rather than the headline number.

Motifs at the end of the run

Motif Residues To active (Å) To inactive (Å) s First half to second Label Secondary structure leans Nearest active / inactive
A-loop 26, 381 to 409 15.74 7.13 -0.377 -0.359 to -0.344 inactive inactive 2HZ4 / 3QRJ
alphaC 11, 282 to 292 1.81 1.26 -0.178 -0.153 to -0.181 intermediate 4TWP / 2HZ0
c.l 8, 361 to 368 2.06 1.64 -0.113 -0.071 to -0.123 intermediate 2HZ4 / 3QRI
g.l 6, 249 to 254 2.45 2.31 -0.029 -0.001 to -0.022 intermediate 4TWP / 3CS9
hinge 3, 316 to 318 0.52 0.27 -0.316 -0.318 to -0.256 inactive 2HZ4 / 3PYY
xDFG 4, 380 to 383 4.82 1.27 -0.584 -0.511 to -0.631 inactive 2HZ4 / 5HU9
What this shows

The last frame, motif by motif, with the distances the score is computed from and the nearest reference structure in each ensemble.

At 49.9 ns, the last frame analysed. A label is decided beyond s = ±0.2; inside that the motif reads as intermediate, which is a measurement and not a missing answer. The two half means say whether a motif was still moving: one number at the end cannot distinguish a motif that settled from one that was on its way somewhere. The last column is left blank where too few residues distinguish the reference sets to read a state from their secondary structure.

What the published criteria measured

Measurement At the start At the end Change State at the end
Lys271 to Glu286 2.77Å 4.81Å +2.04 out
alphaC axis rotation 6.80° 7.70° +0.90
alphaC centroid shift 1.67Å 1.50Å -0.17
P-loop tip to hinge 15.67Å 16.06Å +0.39
R-spine broken broken
What this shows

The measurements every state call on this page is made from, at the first frame and the last. Each residue was resolved at run time from a KLIFS pocket position or a GPCRdb generic number, so the labels name the actual residues rather than a motif in the abstract. This is where a reader checks that the score agrees with the geometry.

Every residue here was resolved at run time from KLIFS pocket positions or GPCRdb generic numbers, which is why the labels name actual residues. A measurement with no reading at either end is left out rather than shown empty.

The ligand, as the reference-state analysis saw it

Residue name STI
Heavy atoms 37
Pose RMSD at the end 0.66 Å
Widest pose RMSD 2.27 Å
Symmetry corrected yes
Contact cutoff 4.0 Å
LYS271 100% of frames, closest 2.75 Å
THR315 100% of frames, closest 2.71 Å
PHE317 100% of frames, closest 2.97 Å
MET318 100% of frames, closest 2.72 Å
ASP381 100% of frames, closest 2.67 Å
ALA269 100% of frames, closest 2.93 Å
MET290 100% of frames, closest 3.01 Å
ALA380 98% of frames, closest 3.03 Å
ILE313 98% of frames, closest 3.17 Å
GLU286 97% of frames, closest 2.63 Å
LEU370 96% of frames, closest 3.21 Å
PHE382 94% of frames, closest 2.91 Å
What this shows

The pose and the contacts are plotted above by the Analysis tab's own ligand panels. This is what those panels do not say: whether the RMSD was symmetry corrected, what cutoff a contact was counted at, and how close each persistent contact actually came.

A contact is counted when any heavy atom of the ligand comes within the cutoff of any heavy atom of a residue, and the closest approach is printed to two decimals: at one, a contact at the cutoff prints as the cutoff and reads as no contact.

Secondary structure, motifs and the reference consensus

What this shows

Secondary structure per residue per frame, with each motif marked down the left edge and the reference ensembles' own consensus in the two columns on the right. A motif whose secondary structure matches the inactive references and not the active ones is the clearest evidence this analysis produces, and it is visible along a row.

Reference state map

What this shows

The reference structures on the plane their published criterion is drawn on, coloured by what the catalogue calls them, with this run's path across it in dark grey. This is the panel where a threshold that does not separate the clusters is obvious rather than argued about.

Superposition core

Core residues 43
Core defined by KLIFS pocket scaffold, excluding GK, a.l, alphaC, b.l, c.l, g.l, hinge, xDFG
Alignment target 2HYY
References aligned 19
References dropped 0
Mean core RMSD 0.42 Å
Worst core RMSD 0.84 Å
Rigidity reference 2E2B
Mean rigidity RMSD 0.46 Å
Worst rigidity RMSD 0.856 Å (2V7A)
What this shows

What every distance on this page was measured after superposing on, and how well the reference structures agree about it.

The core is the part of the fold that does not move between states, so superposing on it leaves the motifs free to.

Reference structures

PDB Chain Resolution (Å) KLIFS state Our state KLIFS DFG Our DFG Agreement In the ensemble
2E2B B 2.20 out out out out agrees not used
2F4J A 1.91 in in in in agrees not used
2G1T B 1.80 in in in in agrees not used
2GQG A 2.40 in in in in agrees not used
2HIW A 2.20 out out out out agrees not used
2HYY C 2.40 out out out out agrees not used
2HZ0 A 2.10 out out out out agrees not used
2HZ4 B 2.80 in in in in agrees not used
2V7A B 2.50 in in no opinion not used
3CS9 C 2.21 out out out out agrees not used
3PYY A 1.85 out out out out agrees not used
3QRI A 2.10 out out no opinion not used
3QRJ B 1.82 out out out out agrees not used
3QRK A 2.30 out out out out agrees not used
4TWP B 2.40 in in in in agrees not used
5HU9 A 1.53 out out no opinion not used
5MO4 A 2.17 out out out out agrees not used
6NPE A 2.15 out out out out agrees not used
6NPU A 2.33 out out out out agrees not used
6NPV A 1.86 out out out out agrees not used
What this shows

The ensemble this run was scored against, and whether our spatial label agrees with the annotation each structure came with. Counted, that agreement is the positive control for the whole method: if the labels did not reproduce the catalogue on structures whose state is known, nothing this page says about a trajectory would mean anything.

20 structures, resolved at run time from the catalogue rather than listed in the code. P1 and P2: our spatial DFG and alphaC labels agree with KLIFS on 17 of 17 structures that carry one. Both labels are measurements here and annotations there. A structure reads "not used" when it has no usable state label or the alignment dropped it; the core panel says how many that was.