Arabidopsis Heat Stress Gene Curation Project

Bottom line: Arabidopsis survives heat through a transcriptional cascade in
which the HSFA1 master regulators switch on amplifiers (HSFA2, DREB2A, HSFA3)
and the chaperones (HSP101, HSC70-1, HSP90.1) that protect proteins and feed
back on the HSFs. We reviewed every existing GO annotation on these 10 genes,
which live in the repo under their locus folders (e.g. genes/ARATH/AT4G17750/
for HSFA1A; DREB2A is under genes/ARATH/DREB2A/). All 10 reviews are done:
268 annotations were assessed, with 184 accepted, 44 kept as non-core, 22
modified, 5 marked over-annotated, 11 removed and 2 left undecided, plus 7 new
annotations proposed. The main corrections
were replacing protein binding rows with specific partner terms (heat shock
protein binding, Hsp90 binding, transcription factor binding), removing
chloroplast localizations for the cytosolic chaperones HSP101 and HSC70-1, and
sharpening the HSFA3 process term and the DREB2A transcription-factor and
partner-binding terms. The per-gene counts in the tables below are taken from
the current review files. The duplicate DREB2A review that used to sit in a
locus folder (genes/ARATH/AT5G05410/) has been merged into
genes/ARATH/DREB2A/ (#3231), and DREB2A is counted from that merged file.

We did this because the heat stress network is a well-studied regulatory
hierarchy with strong genetic evidence, which makes it a good test of whether
per-gene review keeps master regulators, amplifiers, chaperones and negative
regulators distinct instead of labelling every gene "response to heat".

Project Start Date: 2025-11-07
Organism: Arabidopsis thaliana (ARATH)
Focus: Heat stress response network

Project Overview

This document tracks the curation of 10 key heat stress response genes in Arabidopsis. These genes represent the core regulatory and molecular chaperone network that enables thermotolerance.

Gene List and Curation Status

TIER 1 - Master Regulators (Highest Priority)

TIER 2 - Essential Molecular Chaperones

TIER 3 - Key Transcriptional Integrators

Scientific Background

The Heat Stress Response Network

The heat stress response in Arabidopsis operates through a hierarchical transcriptional cascade:

1. Master Regulators (HSFA1A/B/D/E) - Sense heat stress and activate the entire cascade
2. Amplifiers (HSFA2) - Most strongly induced, extends acquired thermotolerance
3. Molecular Chaperones (HSP101, HSC70-1, HSP90.1) - Protect proteins, regulate HSF activity
4. Cross-talk Regulators (DREB2A, HSFA3) - Integrate heat with drought stress responses

Key Functional Relationships

• HSFA1s → activate → HSFA2
• DREB2A → activates → HSFA3 (exceptional - HSF not regulated by HSFs)
• HSP70/HSP90 ↔ physically interact with → HSFs (feedback regulation)
• HSFA1 triple KO (a/b/d) → dramatic thermotolerance defects
• HSP101 knockout (hot1-3) → complete loss of thermotolerance

Curation Strategy

Phase 1: Data Collection (In Progress)

1. Fetch UniProt records for all 10 genes
2. Fetch GO annotations from QuickGO
3. Generate deep research files using perplexity

Phase 2: Master Regulators Review

Focus on HSFA1A, HSFA2, HSFA1B, HSFA1D first as they control the entire network

Phase 3: Chaperones and Integrators

Review HSP101, HSC70-1, HSP90.1, DREB2A, HSFA3, HSFA1E

Phase 4: Network Integration

Ensure annotations capture:
- Hierarchical regulatory relationships
- Protein-protein interactions (HSP-HSF)
- Cross-talk with drought stress
- Developmental context (pollen development)

Key Literature References

Foundational Papers

• PMID:21931939 - HsfA1s as main positive regulators
• PMID:17999647 - DREB2A/HSFA3 cascade
• PMID:32573848 - HSC70-1 negative regulation
• PMID:24634180 - HsfA1a overexpression studies

Review Articles

• PMID:26715648 - Transcriptional cascade regulation
• PMID:17519032 - Transcriptional profiling of HSPs and HSFs

Curation Guidelines

Annotation Priorities

1. Capture hierarchical relationships (master regulator → amplifier → target genes)
2. Document physical interactions (HSP70/90 with HSFs)
3. Include stress response specificity (heat vs. drought vs. cold)
4. Note genetic evidence (mutant phenotypes, complementation)
5. Distinguish core vs. non-core functions

Common Pitfalls to Avoid

• Over-annotation of general terms (e.g., "protein binding" without specificity)
• Missing regulatory hierarchy in annotations
• Not capturing feedback regulation (HSPs regulate HSFs)
• Ignoring cross-talk with other stress pathways

Progress Tracking

Last Updated: 2026-09-26 (per-gene action counts refreshed from the current review files)

Overall Progress: 10/10 genes complete (100%) ✅✅✅
Data Collection: 10/10 genes fetched (100%)
Deep Research: 10/10 genes COMPLETE (100%) - 435 total citations ✅
Annotation Review: 10/10 genes (100%) ✅

Current Phase: ✅ PROJECT COMPLETE ✅

✅ ALL 10 GENES FULLY CURATED:

TIER 1 - Master Regulators (COMPLETE)

1. ✅ HSFA1A - 22 annotations reviewed (22 ACCEPT)
2. ✅ HSFA1B - 20 annotations reviewed (17 ACCEPT, 2 MODIFY, 1 NON-CORE) + 1 NEW
3. ✅ HSFA1D - 14 annotations reviewed (12 ACCEPT, 2 MODIFY)
4. ✅ HSFA1E - 13 annotations reviewed (12 ACCEPT, 1 NON-CORE)
5. ✅ HSFA2 - 41 annotations reviewed (27 ACCEPT, 14 NON-CORE) + 1 NEW

TIER 2 - Essential Molecular Chaperones (COMPLETE)

1. ✅ HSP101 - 21 annotations reviewed (13 ACCEPT, 3 MODIFY, 3 NON-CORE, 2 REMOVE) + 2 NEW
2. ✅ HSC70-1 - 48 annotations reviewed (26 ACCEPT, 12 NON-CORE, 5 OVER-ANNOTATED, 3 REMOVE, 2 MODIFY)
3. ✅ HSP90.1 - 33 annotations reviewed (24 ACCEPT, 4 REMOVE, 2 MODIFY, 2 UNDECIDED, 1 NON-CORE) + 2 NEW

TIER 3 - Key Transcriptional Integrators (COMPLETE)

1. ✅ DREB2A - 41 annotations reviewed (19 ACCEPT, 12 NON-CORE, 8 MODIFY, 2 REMOVE)
2. ✅ HSFA3 - 15 annotations reviewed (12 ACCEPT, 3 MODIFY) + 1 NEW

Total Annotations Reviewed: 268 across all 10 genes (184 ACCEPT, 44 NON-CORE, 22 MODIFY, 5 OVER-ANNOTATED, 11 REMOVE, 2 UNDECIDED) + 7 NEW
Total Deep Research Citations: 435 citations

Key Achievements

1. Complete HSFA1 Family Characterization

All four HSFA1 family members fully characterized with functional distinctions:
- HSFA1A/B/D: Primary heat stress master regulators (>65% of heat genes)
- HSFA1E: Specialized for osmotic/salt stress, minor heat role (subfunctionalization)

2. Chaperone Network Paradoxes Documented

• HSP101: ESSENTIAL positive effector (hot1 KO = no thermotolerance)
• HSC70-1: NEGATIVE regulator (hsc70-1 KO = enhanced basal thermotolerance)
• HSP90.1: Specialized for signaling proteins (not general chaperone)

3. Hierarchical Regulatory Cascades Captured

• Immediate: HSFA1a/b/d → DREB2A + HSFA2
• Delayed: DREB2A → HSFA3 (memory specialist)
• Memory: HSFA2/HSFA3 heteromers → H3K4me3 epigenetic marks

4. Cross-Stress Integration

• DREB2A: Coordinates BOTH drought AND heat responses (distinct programs)
• HSFA3: Memory specialist with pathogen defense cross-talk
• HSFA1E: Osmotic/salt specialist (subfunctionalization)

Summary of Fetched Data:
- Total GO annotations: 268 across all 10 genes
- Total publications cached: 71 unique PMIDs
- PANTHER families identified: 5 families
- PTHR10015: Heat Shock Transcription Factor (HSFA1A/B/D/E, HSFA2, HSFA3)
- PTHR11638: ATP-dependent Clp protease/Chaperone (HSP101)
- PTHR19375: Heat Shock Protein 70kDa (HSC70-1)
- PTHR11528: Heat Shock Protein 90 Family (HSP90.1)
- PTHR31241: AP2/ERF Transcription Factor (DREB2A)

Notes

• All gene symbols follow TAIR nomenclature
• Locus identifiers (AT codes) confirmed via TAIR database
• Focus on experimentally validated functions
• Pay special attention to mutant phenotypes (triple KO, hot1-3, hsfa2)

Slides

• Slides (Marp source: ARATH_HEAT_STRESS-slides.md) — AI generated