TY - JOUR
T1 - The Sheaths of Methanospirillum Are Made of a New Type of Amyloid Protein
AU - Christensen, Line Friis Bakmann
AU - Hansen, Lonnie Maria
AU - Finster, Kai
AU - Christiansen, Gunna
AU - Nielsen, Per Halkjær
AU - Otzen, Daniel Erik
AU - Dueholm, Morten Simonsen
PY - 2018/11/13
Y1 - 2018/11/13
N2 - The genera Methanospirillum and Methanosaeta contain species of anaerobic archaea that grow and divide within proteinaceous tubular sheaths that protect them from environmental stressors. The sheaths of Methanosaeta thermophila PT are composed of the 60.9 kDa major sheath protein MspA. In this study we show that sheaths purified from Methanospirillum hungatei JF-1 are regularly striated tubular structures with amyloid-like properties similar to those of Methanosaeta thermophila PT. Depolymerizing the sheaths from M. hungatei JF-1 allowed us to identify a 40.6 kDa protein (WP_011449234.1) that shares 23% sequence similarity to MspA from M. thermophila PT (ABK14853.1), indicating that they might be distant homologs. The genome of M. hungatei JF-1 encodes six homologs of the identified MspA protein. Several homologs also exist in the related strains Methanospirillum stamsii (7 homologs, 28-66% sequence identity), Methanospirillum lacunae (15 homologs, 29-60% sequence identity) and Methanolinea tarda (2 homologs, 31% sequence identity). The MspA protein discovered here could accordingly represent a more widely found sheath protein than the MspA from M. thermophila PT, which currently has no homologs in the NCBI Reference Sequence database (RefSeq).
AB - The genera Methanospirillum and Methanosaeta contain species of anaerobic archaea that grow and divide within proteinaceous tubular sheaths that protect them from environmental stressors. The sheaths of Methanosaeta thermophila PT are composed of the 60.9 kDa major sheath protein MspA. In this study we show that sheaths purified from Methanospirillum hungatei JF-1 are regularly striated tubular structures with amyloid-like properties similar to those of Methanosaeta thermophila PT. Depolymerizing the sheaths from M. hungatei JF-1 allowed us to identify a 40.6 kDa protein (WP_011449234.1) that shares 23% sequence similarity to MspA from M. thermophila PT (ABK14853.1), indicating that they might be distant homologs. The genome of M. hungatei JF-1 encodes six homologs of the identified MspA protein. Several homologs also exist in the related strains Methanospirillum stamsii (7 homologs, 28-66% sequence identity), Methanospirillum lacunae (15 homologs, 29-60% sequence identity) and Methanolinea tarda (2 homologs, 31% sequence identity). The MspA protein discovered here could accordingly represent a more widely found sheath protein than the MspA from M. thermophila PT, which currently has no homologs in the NCBI Reference Sequence database (RefSeq).
KW - Archaea
KW - Functional amyloid
KW - Homologs
KW - Methanogen
KW - Sheath protein
UR - http://www.scopus.com/inward/record.url?scp=85056734961&partnerID=8YFLogxK
U2 - 10.3389/fmicb.2018.02729
DO - 10.3389/fmicb.2018.02729
M3 - Journal article
SN - 1664-302X
VL - 9
JO - Frontiers in Microbiology
JF - Frontiers in Microbiology
IS - NOV
M1 - 02729
ER -