GO_REF:0000024

Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:20550936

A mammalian siderophore synthesized by an enzyme with a bacterial homolog involved in enterobactin production.

BDH2 is homologous to bacterial EntA and participates in mammalian/eukaryotic siderophore synthesis.

"The iron-binding moiety of the mammalian siderophore is 2,5-DHBA"
Siderophore-depleted zebrafish embryos fail to synthesize heme.

"zebrafish embryos fail to synthesize"

PMID:26929344

Inactivation of 3-hydroxybutyrate dehydrogenase 2 delays zebrafish erythroid maturation by conferring premature mitophagy.

Bdh2 catalyzes a rate-limiting step in eukaryotic siderophore biogenesis, and bdh2 inactivation causes heme deficiency and delayed erythroid maturation.

"(Bdh2), catalyzes a rate-limiting step in the biogenesis of the eukaryotic"

file:DANRE/bdh2/bdh2-uniprot.txt

UniProtKB entry Q561X9 for Danio rerio bdh2

UniProt describes separate Bdh2 roles in 4-oxo-L-proline reduction and 2,5-DHBA siderophore formation.

"formation of 2,5-dihydroxybenzoate (2,5-DHBA)"

file:DANRE/bdh2/bdh2-deep-research-falcon.md

Falcon deep research on zebrafish bdh2 (Edison Scientific Literature)

Bdh2 is the rate-limiting NAD-dependent enzyme producing the endogenous catecholate siderophore 2,5-DHBA, an iron-coordinating ligand; it is a functional homolog of bacterial EntA.

"BDH2 catalyzes a **rate-limiting NAD-dependent step** in biosynthesis of **2,5-dihydroxybenzoic acid (2,5-DHBA)**, an endogenous catecholate that can coordinate iron "
Bdh2 enzymology is linked to catecholate siderophore chemistry through homology to bacterial EntA.

"BDH2 is a functional homolog of **bacterial EntA**, linking its enzymology to catecholate siderophore chemistry "
The conserved BDH2 role is siderophore-dependent iron handling rather than ketone-body oxidation; BDH2 is only ~20% identical to mitochondrial BDH1 and is dispensable for ketone-body metabolism in vivo.

"is described as only ~20% identical to mitochondrial BDH1 and is considered dispensable for ketone-body metabolism in vivo in the mouse knockout study "
Zebrafish bdh2 knockdown causes hypochromic blood and markedly reduced o-dianisidine (heme) staining, rescued by MO-resistant bdh2 mRNA.

"morpholino knockdown causes **hypochromic blood** and **markedly reduced o-dianisidine staining** "
The hemoglobinization phenotype reflects impaired heme/iron handling rather than globin transcription, because hbae1/hbae3 globin genes are expressed normally in bdh2 morphants.

"globin genes (**hbae1/hbae3**) were reported as expressed normally, suggesting the phenotype reflects impaired heme/iron handling rather than globin transcription "
In zebrafish erythrocytes, bdh2 loss causes mitochondrial dysfunction followed by premature mitochondrial clearance via mitophagy.

"loss of bdh2 causes mitochondrial dysfunction followed by **premature mitochondrial clearance via mitophagy** "
Suppressing autophagy via atg7 knockdown reduces mitochondrial clearance and partially rescues hemoglobinization and erythroid maturation (N:C ratios), placing erythroid maturation downstream of mitochondrial iron metabolism.

"suppressing autophagy via **atg7** knockdown reduces mitochondrial clearance and partially rescues hemoglobinization and N:C ratios "
The best current (ortholog-informed) localization model places BDH2 as a cytosolic/outer-mitochondrial-membrane enzyme enriched at mitochondria-lysosome contact sites coordinating lysosome-to-mitochondria iron transfer; not yet directly demonstrated in zebrafish.

"cytosolic/outer-mitochondrial-membrane-associated enzyme enriched at **mitochondria–lysosome contact sites** "