PMID- 11790772
OWN - NLM
STAT- MEDLINE
DCOM- 20020510
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 277
IP  - 13
DP  - 2002 Mar 29
TI  - Identification of amino acid residues critical for biological activity in human 
      interleukin-18.
PG  - 10998-1003
AB  - Interleukin-18 (IL-18) is a pro-inflammatory cytokine, and IL-18-binding protein 
      (IL-18BP) is a naturally occurring protein that binds IL-18 and neutralizes its 
      biological activities. Computer modeling of human IL-18 identified two charged 
      residues, Glu-42 and Lys-89, which interact with oppositely charged amino acid 
      residues buried in a large hydrophobic pocket of IL-18BP. The cell surface IL-18 
      receptor alpha chain competes with IL-18BP for IL-18 binding, although the IL-18 
      receptor alpha chain does not share significant homology to IL-18BP. In the 
      present study, Glu-42 was mutated to Lys and Lys-89 to Glu; Glu-42 and Lys-89 
      were also deleted separately. The deletion mutants (E42X and K89X) were devoid of 
      biological activity, and the K89E mutant lost 95% of its activity. In contrast, 
      compared with wild-type (WT) IL-18, the E42K mutant exhibited a 2-fold increase 
      in biological activity and required a 4-fold greater concentration of IL-18BP for 
      neutralization. The binding of WT IL-18 and its various mutants to human natural 
      killer cells was evaluated by competition assays. The mutant E42K was more 
      effective than WT IL-18 in inhibiting the binding of (125)I-IL-18 to natural 
      killer cells, whereas the three inactive mutants E42X, K89E, and K89X were unable 
      to compete with (125)I-IL-18 for binding. Similarly, WT IL-18 and the E42K mutant 
      induced degradation of Ikappa-Balpha, whereas the three biologically inactive 
      mutants did not induce degradation. The present study reveals that Glu-42 and 
      Lys-89 are critical amino acid residues for the integrity of IL-18 structure and 
      are important for binding to cell surface receptors, for signal transduction, and 
      for neutralization by IL-18BP.
FAU - Kim, Soo-Hyun
AU  - Kim SH
AD  - University of Colorado Health Sciences Center, Denver, Colorado 80262, USA. 
      soohyun.kim@UCHSC.edu
FAU - Azam, Tania
AU  - Azam T
FAU - Novick, Daniela
AU  - Novick D
FAU - Yoon, Do-Young
AU  - Yoon DY
FAU - Reznikov, Leonid L
AU  - Reznikov LL
FAU - Bufler, Philip
AU  - Bufler P
FAU - Rubinstein, Menachem
AU  - Rubinstein M
FAU - Dinarello, Charles A
AU  - Dinarello CA
LA  - eng
GR  - AI-15614/AI/NIAID NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
DEP - 20020114
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (DNA Primers)
RN  - 0 (DNA-Binding Proteins)
RN  - 0 (I-kappa B Proteins)
RN  - 0 (Interleukin-18)
RN  - 0 (NFKBIA protein, human)
RN  - 139874-52-5 (NF-KappaB Inhibitor alpha)
SB  - IM
MH  - Amino Acid Sequence
MH  - Base Sequence
MH  - DNA Primers
MH  - DNA-Binding Proteins/metabolism
MH  - Humans
MH  - Hydrolysis
MH  - *I-kappa B Proteins
MH  - Interleukin-18/chemistry/genetics/*physiology
MH  - Molecular Sequence Data
MH  - Mutagenesis
MH  - NF-KappaB Inhibitor alpha
MH  - Sequence Homology, Amino Acid
MH  - Structure-Activity Relationship
EDAT- 2002/01/16 10:00
MHDA- 2002/05/11 10:01
CRDT- 2002/01/16 10:00
PHST- 2002/01/16 10:00 [pubmed]
PHST- 2002/05/11 10:01 [medline]
PHST- 2002/01/16 10:00 [entrez]
AID - S0021-9258(18)52117-7 [pii]
AID - 10.1074/jbc.M108311200 [doi]
PST - ppublish
SO  - J Biol Chem. 2002 Mar 29;277(13):10998-1003. doi: 10.1074/jbc.M108311200. Epub 
      2002 Jan 14.