SIS2
S. cerevisiae
phosphopantothenoylcysteine decarboxylase complex subunit SIS2
What the model saw
Gene: SIS2 Organism: Saccharomyces cerevisiae Known functions: phosphopantothenoylcysteine decarboxylase complex subunit SIS2. FMN binding. catalytic activity. identical protein binding. phosphopantothenoylcysteine decarboxylase activity. protein binding. protein serine/threonine phosphatase inhibitor activity.
View unredacted entry
phosphopantothenoylcysteine decarboxylase complex subunit SIS2. FMN binding. catalytic activity. identical protein binding. phosphopantothenoylcysteine decarboxylase activity. protein binding. protein serine/threonine phosphatase inhibitor activity.
Solver output
SIS2 encodes a subunit of the phosphopantothenoylcysteine (PPC) decarboxylase complex, which catalyzes a key step in the biosynthesis of Coenzyme A (CoA) from pantothenate. CoA is a central metabolic cofactor essential for fatty acid metabolism, the TCA cycle, and acetyl-CoA production, all of which are tightly linked to nutrient sensing and metabolic homeostasis. Additionally, SIS2 has protein serine/threonine phosphatase inhibitor activity, which connects it to signaling regulation — notably, SIS2 is known to inhibit the Sit4 phosphatase, a downstream effector of TORC1 signaling. Inhibition of Sit4 modulates the activity of Hal3/Ppz phosphatases and influences stress responses and ion homeostasis. By participating in CoA biosynthesis and restraining TORC1-downstream phosphatase activity, SIS2 supports metabolic balance and stress resilience, both of which are associated with extended lifespan in yeast. The dual role in CoA production (supporting NAD+/acetyl-CoA metabolism) and phosphatase inhibition (modulating TOR pathway output) places SIS2 in a pro-longevity context.
GenAge curators classify each gene's normal function as promoting (Pro-Longevity) or opposing (Anti-Longevity) longevity, based on synthesis across studies. Loss-of-function effects can vary from this depending on the manipulation.
Advisor judgment
The model predicted pro_longevity but the ground truth is anti_longevity. SIS2 is actually anti-longevity in yeast - deletion of SIS2 extends lifespan. The model's reasoning about SIS2 supporting metabolic balance and stress resilience leading to pro-longevity effects is incorrect. While the model correctly identifies SIS2's role in CoA biosynthesis and Sit4 phosphatase inhibition, it draws the wrong conclusion about the longevity direction. SIS2 inhibits Sit4 phosphatase, which is a downstream effector of TORC1 - but the model incorrectly reasons that this inhibition is pro-longevity. In reality, SIS2 (as an inhibitor of Sit4) would promote TORC1-like signaling effects, which are generally anti-longevity. The model had moderate confidence (0.62) but still got the direction wrong. The mechanistic reasoning about the Sit4/TORC1 pathway is partially correct in identifying the pathway but wrong in the directional interpretation of its effect on longevity.
Raw API responses
solver
{
"reasoning": "SIS2 encodes a subunit of the phosphopantothenoylcysteine (PPC) decarboxylase complex, which catalyzes a key step in the biosynthesis of Coenzyme A (CoA) from pantothenate. CoA is a central metabolic cofactor essential for fatty acid metabolism, the TCA cycle, and acetyl-CoA production, all of which are tightly linked to nutrient sensing and metabolic homeostasis. Additionally, SIS2 has protein serine/threonine phosphatase inhibitor activity, which connects it to signaling regulation — notably, SIS2 is known to inhibit the Sit4 phosphatase, a downstream effector of TORC1 signaling. Inhibition of Sit4 modulates the activity of Hal3/Ppz phosphatases and influences stress responses and ion homeostasis. By participating in CoA biosynthesis and restraining TORC1-downstream phosphatase activity, SIS2 supports metabolic balance and stress resilience, both of which are associated with extended lifespan in yeast. The dual role in CoA production (supporting NAD+/acetyl-CoA metabolism) and phosphatase inhibition (modulating TOR pathway output) places SIS2 in a pro-longevity context.",
"confidence": 0.62,
"key_pathways": [
"CoA biosynthesis / pantothenate metabolism",
"TORC1-Sit4 phosphatase signaling",
"FMN-dependent decarboxylase activity"
],
"mechanism_class": "deregulated_nutrient_sensing",
"longevity_influence": "pro_longevity"
}advisor
{
"notes": "The model predicted pro_longevity but the ground truth is anti_longevity. SIS2 is actually anti-longevity in yeast - deletion of SIS2 extends lifespan. The model's reasoning about SIS2 supporting metabolic balance and stress resilience leading to pro-longevity effects is incorrect. While the model correctly identifies SIS2's role in CoA biosynthesis and Sit4 phosphatase inhibition, it draws the wrong conclusion about the longevity direction. SIS2 inhibits Sit4 phosphatase, which is a downstream effector of TORC1 - but the model incorrectly reasons that this inhibition is pro-longevity. In reality, SIS2 (as an inhibitor of Sit4) would promote TORC1-like signaling effects, which are generally anti-longevity. The model had moderate confidence (0.62) but still got the direction wrong. The mechanistic reasoning about the Sit4/TORC1 pathway is partially correct in identifying the pathway but wrong in the directional interpretation of its effect on longevity.",
"failure_mode": "confident_wrong",
"answer_correct": false,
"mechanism_correct": false,
"reasoning_quality": 2,
"ground_truth_questionable": false
}