The Chediak-Higashi protein interacts with SNARE complex and signal transduction proteins.
BACKGROUND
Chediak-Higashi syndrome (CHS) is an inherited immunodeficiency disease characterized by giant lysosomes and impaired leukocyte degranulation. CHS results from mutations in the lysosomal trafficking regulator (LYST) gene, which encodes a 425-kD cytoplasmic protein of unknown function. The goal of this study was to identify proteins that interact with LYST as a first step in understanding how LYST modulates lysosomal exocytosis.


METHODS
Fourteen cDNA fragments, covering the entire coding domain of LYST, were used as baits to screen five human cDNA libraries by a yeast two-hybrid method, modified to allow screening in the activation and the binding domain, three selectable markers, and more stringent confirmation procedures. Five of the interactions were confirmed by an in vitro binding assay.


RESULTS
Twenty-one proteins that interact with LYST were identified in yeast two-hybrid screens. Four interactions, confirmed directly, were with proteins important in vesicular transport and signal transduction (the SNARE-complex protein HRS, 14-3-3, and casein kinase II).


CONCLUSIONS
On the basis of protein interactions, LYST appears to function as an adapter protein that may juxtapose proteins that mediate intracellular membrane fusion reactions. The pathologic manifestations observed in CHS patients and in mice with the homologous mutation beige suggest that understanding the role of LYST may be relevant to the treatment of not only CHS but also of diseases such as asthma, urticaria, and lupus, as well as to the molecular dissection of the CHS-associated cancer predisposition.
Tchernev
Velizar T
VT
CuraGen Corporation, New Haven, CT 06511, USA. velizart@molecularstaging.com
Mansfield
Traci A
TA
Giot
Loic
L
Kumar
A Madan
AM
Nandabalan
Krishnan
K
Li
Ying
Y
Mishra
Vishnu S
VS
Detter
John C
JC
Rothberg
Jonathan M
JM
Wallace
Margaret R
MR
Southwick
Frederick S
FS
Kingsmore
Stephen F
SF
D048948:14-3-3 Proteins; D000818:Animals; D047390:Casein Kinase II; D018076:DNA, Complementary / Q000235:genetics; D056827:Endosomal Sorting Complexes Required for Transport; D005089:Exocytosis / Q000502:physiology; D015723:Gene Library; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008247:Lysosomes / Q000378:metabolism; D046911:Macromolecular Substances; D051379:Mice; D010446:Peptide Fragments / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D019210:Troponin I / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*; D033921:Vesicular Transport Proteins
D048948:14-3-3 Proteins; D018076:DNA, Complementary; D056827:Endosomal Sorting Complexes Required for Transport; D047908:Intracellular Signaling Peptides and Proteins; C102161:LYST protein, human; C491133:Lyst protein, mouse; D046911:Macromolecular Substances; D010446:Peptide Fragments; D010750:Phosphoproteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D019210:Troponin I; D033921:Vesicular Transport Proteins; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate; D014446:Tyrosine 3-Monooxygenase; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases