Spätzle (gene)

Spätzle or spaetzle (German for a type of noodle) is an evolutionarily-conserved arthropod protein first identified in Drosophila melanogaster.^[1] It plays a role in embryonic development and in the insect innate immune response. The name was coined by the Nobel laureate Christiane Nüsslein-Volhard after the Spätzle noodle-like form of homozygous mutant fly larvae.^[2]

Spätzle (gene)
Identifiers
Organism	Drosophila melanogaster
Symbol	spz
UniProt	P48607
Search for Structures Swiss-model Domains InterPro

Spätzle
Identifiers
Symbol	Spaetzle
Pfam	PF16077
InterPro	IPR032104
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Toll signaling pathways in mammals, shrimp and fruit flies

Structure

Spätzle has a cystine knot structure supported by disulfide bridges, is glycosylated, and naturally forms a homodimer. Multiple forms are produced by alternative splicing.^[3] It is produced as a preprotein, and needs to be activated by a serine protease called spätzle-processing enzyme [de]. The signal sequence spz[1-25] is first cleaved, followed by the spz[26-220] fragment, leaving the final spz[221-326] (Spaetzle C-106) part as the mature protein.^[4]

Function

Homodimeric spz binds to a dimeric toll receptor in fruit flies and related organisms, thus activating the signaling cascade.^[5]

Embryonic development

A ligand of the toll pathway, spz is involved in the formation of the dorso-ventral axis in embryonic development. ^[6]

References

1. Stein D, Nüsslein-Volhard C (February 1992). "Multiple extracellular activities in Drosophila egg perivitelline fluid are required for establishment of embryonic dorsal-ventral polarity". Cell. 68 (3): 429–40. doi:10.1016/0092-8674(92)90181-b. PMID 1739964. S2CID 20617175.
2. "Christiane Nüsslein-Volhard in Biologie | Schülerlexikon | Lernhelfer". www.lernhelfer.de (in German). Retrieved 2019-11-19.
3. DeLotto Y, Smith C, DeLotto R (January 2001). "Multiple isoforms of the Drosophila Spätzle protein are encoded by alternatively spliced maternal mRNAs in the precellular blastoderm embryo". Molecular & General Genetics. 264 (5): 643–52. doi:10.1007/s004380000350. PMID 11212919. S2CID 1456450.
4. P48607
5. Morisato D, Anderson KV (February 1994). "The spätzle gene encodes a component of the extracellular signaling pathway establishing the dorsal-ventral pattern of the Drosophila embryo". Cell. 76 (4): 677–88. doi:10.1016/0092-8674(94)90507-x. PMID 8124709. S2CID 26328826.
6. Morisato, Donald (15 June 2001). "Spätzle regulates the shape of the Dorsal gradient in the Drosophila embryo". Development. 128 (12): 2309–2319. doi:10.1242/dev.128.12.2309. PMID 11493550. Retrieved 10 February 2023.