An oligopeptide transporter of Mycobacterium tuberculosis regulates cytokine release and apoptosis of infected macrophages.
BACKGROUND
The Mycobacterium tuberculosis genome encodes two peptide transporters encoded by Rv3665c-Rv3662c and Rv1280c-Rv1283c. Both belong to the family of ABC transporters containing two nucleotide-binding subunits, two integral membrane proteins and one substrate-binding polypeptide. However, little is known about their functions in M. tuberculosis. Here we report functional characterization of the Rv1280c-Rv1283c-encoded transporter and its substrate-binding polypeptide OppA(MTB).


RESULTS
OppA(MTB) was capable of binding the tripeptide glutathione and the nonapeptide bradykinin, indicative of a somewhat broad substrate specificity. Amino acid residues G109, N110, N230, D494 and F496, situated at the interface between domains I and III of OppA, were required for optimal peptide binding. Complementaton of an oppA knockout mutant of M. smegmatis with OppA(MTB) confirmed the role of this transporter in importing glutathione and the importance of the aforesaid amino acid residues in peptide transport. Interestingly, this transporter regulated the ability of M. tuberculosis to lower glutathione levels in infected compared to uninfected macrophages. This ability was partly offset by inactivation of oppD. Concomitantly, inactivation of oppD was associated with lowered levels of methyl glyoxal in infected macrophages and reduced apoptosis-inducing ability of the mutant. The ability to induce the production of the cytokines IL-1beta, IL-6 and TNF-alpha was also compromised after inactivation of oppD.


CONCLUSIONS
Taken together, these studies uncover the novel observations that this peptide transporter modulates the innate immune response of macrophages infected with M. tuberculosis.
Dasgupta
Arunava
A
Unité de Génétique Mycobactérienne, Institut Pasteur, Paris, France.
Sureka
Kamakshi
K
Mitra
Devrani
D
Saha
Baisakhee
B
Sanyal
Sourav
S
Das
Amit K
AK
Chakrabarti
Parul
P
Jackson
Mary
M
Gicquel
Brigitte
B
Kundu
Manikuntala
M
Basu
Joyoti
J
D017209:Apoptosis; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism*; D004252:DNA Mutational Analysis; D055786:Gene Knockout Techniques; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D008074:Lipoproteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism* / Q000382:microbiology; D008958:Models, Molecular; D009154:Mutation; D020102:Mycobacterium smegmatis / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000378:metabolism* / Q000502:physiology; D011765:Pyruvaldehyde / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D001426:Bacterial Proteins; D002352:Carrier Proteins; D016207:Cytokines; D008074:Lipoproteins; C046506:oligopeptide-binding protein, bacteria; D011765:Pyruvaldehyde; D005978:Glutathione
Structure. 1995 Dec 15;3(12):1395-406
8747465
Biochemistry. 1995 Dec 26;34(51):16585-95
8527431
J Bacteriol. 1991 Feb;173(4):1388-98
1899858
Mol Microbiol. 1996 Jun;20(5):919-25
8809745
Nat Med. 2003 Aug;9(8):1039-46
12872166
Trends Biochem Sci. 1998 Nov;23(11):444-7
9852764
J Mol Biol. 1994 Aug 5;241(1):44-58
8051706
Drug Metabol Drug Interact. 2008;23(1-2):125-50
18533367
EMBO J. 2009 May 6;28(9):1332-40
19300437
PLoS One. 2006 Dec 20;1:e29
17183656
J Mol Biol. 2005 Jan 28;345(4):879-92
15588833
FEBS Lett. 2006 Feb 13;580(4):1023-35
16375896
Urol Res. 2002 May;30(2):116-21
12086016
Infect Immun. 1998 Aug;66(8):3626-34
9673242
Acta Crystallogr D Biol Crystallogr. 2007 Nov;63(Pt 11):1185-93
18007034
Biol Chem. 1997 Mar-Apr;378(3-4):317-20
9165087
J Bacteriol. 1993 Dec;175(23):7523-32
8244921
Mol Microbiol. 1991 Jan;5(1):173-85
1901616
FASEB J. 2009 Dec;23(12):4091-104
19671666
Mol Microbiol. 1996 Dec;22(5):881-93
8971710
Biochem J. 1988 Sep 15;254(3):751-5
3196289
Annu Rev Cell Biol. 1992;8:67-113
1282354
J Mol Evol. 1999 Jan;48(1):22-41
9873074
Infect Immun. 2000 Feb;68(2):429-36
10639400
Microbiology (Reading). 2000 Aug;146 ( Pt 8):1969-1975
10931901
Microb Pathog. 2008 Mar;44(3):255-61
17959342
Mol Microbiol. 1990 Nov;4(11):1911-9
2082148
Proc Natl Acad Sci U S A. 2000 Nov 7;97(23):12487-92
11050157
Immunol Lett. 1997 Aug;58(3):139-47
9293394
Mol Cell. 2007 Jun 8;26(5):675-87
17560373
J Bacteriol. 2004 Jan;186(1):51-60
14679224