3.A.7.9.1 The Icm/Dot or Dot/Icm multicomponent protein secretion system. IcmS and IcmW form a complex that interacts with and may translocate substrate proteins (Ninio et al., 2005; De Buck et al., 2007; Cambronne and Roy, 2007). The crystal structure of the IcmR-IcmQ complex has been solved (Raychaudhury et al., 2009). Legionella pneumophila survives and replicates inside host cells by secreting ~300 effectors through the defective in organelle trafficking (Dot)/intracellular multiplication (Icm) type IVB secretion system (T4BSS). Ghosal et al. 2019, using electron cryotomography mapped the location of the core and accessory components of the Legionella core transmembrane subcomplex, revealing a well-ordered central channel that opens into a large, windowed secretion chamber with an unusual 13-fold symmetry. Immunofluorescence microscopy deciphered an early-stage assembly process that begins with the targeting of Dot/Icm components to the bacterial poles. Polar targeting of this T4BSS is mediated by two Dot/Icm proteins, DotU and IcmF, that are homologues of the T6SS membrane complex components TssL and TssM, suggesting that the Dot/Icm T4BSS is a hybrid system. Thus, the Dot/Icm complex assembles in an 'axial-to-peripheral' pattern (Ghosal et al. 2019).
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Accession Number: | Q5ZYC6 |
Protein Name: | DotL aka IcmO |
Length: | 783 |
Molecular Weight: | 87503.00 |
Species: | Legionella pneumophila subsp. pneumophila (strain Philadelphia 1 / ATCC 33152 / DSM 7513) [272624] |
Number of TMSs: | 1 |
Location1 / Topology2 / Orientation3: |
Cell membrane1 / Single-pass membrane protein2 |
Substrate |
protein polypeptide chain |
---|
1: MMRGIDSRHE LDPTLLLRDT RTFTQRLADF FADPTNISIV LISLAAVSYY FSEAATFLLI
61: MGGIFFLYSY TRKQKLPFRL PQISRAKDYN DLKPGINKPN IARGITFFGN DRKTGEELWF
121: ANDDMRTHAL IFGSTGSGKT ETLVSLSYNA LVQGSGFIYV DGKGDNSLYA KVFSMVRSMG
181: REDDLLLINF MTGARDIVGP QEKRLSNTLN PFCQGSSSML TQLVVSLMGS SGQSSDGDMW
241: KGRAIAFVEA LMRLLVYMRD EGAILLDANT IRNYFDLQRL ESIVIDKVFP RDDQESVNIE
301: TIPKLVTDPL RNYLNTLPGY NKEKKGKQVS QVLEQHGFIT MQLVRSFSSL ADTYGHIIRT
361: NLAEVDFKDV VLNRRILVVL LPALEKSPDE LSNLGKIIVS SLKAMMAAGL GEEVEGDYRD
421: VILRKPTNAP TPYMCILDEY GYYAVQGFAV VPAQARSLGF SAIFAGQDLP AFQKASKEEA
481: ASIGANTNIK ICMKLEDPTE TWDFFTKTAG EAYVTKVDSF QTKETSIANS YMDTKSSSFE
541: KRARVDLLDL KEQTEGEAHI FFKSKIVRAR MFYANPKPVK QLKINQFLKV EPPPDDYLMK
601: LQKQLASFQS ILESGDLSIN KAVENEEITL ISKALKESTI VEPIERGVAA LIAFHGQNEP
661: EPVEDIVEEE VEGALTIFSK LRIDPNAPPI LVADKEVFSE PLLPINETRN QMITIERLAG
721: AKDKYAGTVA NELIKDFQIA TSYPPEERDV IDVQELTGII RDLSAKISAE REKANKKAAE
781: ELT