Table 2 Lactyl-CoA synthesis mechanism and influencing factors.

ACSS2 pathway [10]

1. Nuclear Translocation Regulation: EGFR activation triggers ERK-mediated phosphorylation of ACSS2 at S267, promoting importin α5 binding and nuclear translocation.

2. Substrate Binding: ACSS2 binds L-lactate, CoA, and ATP.

3. Intermediate Formation: Lactate carboxyl group reacts with ATP γ-phosphate to form lactyl-AMP intermediate (releasing PPi).

4. CoA Transfer: CoA thiol displaces AMP, generating lactyl-CoA.

Lactate concentration: preferential lactate utilization over acetate/succinate in nuclear compartments.

Structural specificity: changes in conformation between open and closed states affect substrate binding. The closed state enhances lactate/CoA binding, while the open state promotes nuclear translocation.

Key residues: D358 stabilizes lactate hydroxyl; Y645/R533 anchor lactyl group for catalysis.

GTPSCS pathway [11]

1. Nuclear localization: GTPSCS G1 subunit contains NLS (SUCLG1 residues 192–195), directing nuclear entry.

2. Substrate binding: Binds L-lactate, GTP, and CoA.

3. Intermediate formation: Lactate carboxyl group reacts with GTP β-phosphate to form lactyl-GTP (releasing PPi).

4. CoA transfer: CoA thiol replaces GTP γ-phosphate, yielding lactyl-CoA and GDP (releasing Pi).

Lactate preference: higher K_m for lactate (15.3 mM) vs. succinate.

Lactate concentration: nuclear lactate concentration dictates substrate selection.

Key residues: N308 hydrogen-bonds with lactate hydroxyl; G365/V367 stabilize lactate conformation.

LGSH-Mediated [90]

1. GSH cycle: glycolytic intermediate MGO forms LGSH via GSH cycle.

2. Non-enzymatic transfer: LGSH undergoes thiol-disulfide exchange with CoA, generating lactyl-CoA.

GLO2 activity: deficiency drives LGSH accumulation, promoting non-enzymatic S-to-S acyl transfer to CoA.

pH dependency: LGSH-CoA transfer is favored under acidic conditions (pK_a difference between GSH and CoA thiols: 8.4 vs. 9.8).