Protection of Secreted Proteins in Cyanobacteria

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Protection of Secreted Proteins in Cyanobacteria

• Aaron Holman

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How do cells secrete proteins?

• Signal sequence

• Most use Sec pathway

• Some use TAT pathway

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Why?

• Harsh conditions inhibit folding

• Archae, Bacteria (Cyanobacteria)

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Goals

• How do cyanobacteria protect secreted proteins?
• What kind of proteins use the TAT patway?

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What is the TAT signal?

• (S/T)RRxFLKNon-hydrophobic

QRSKKSRRTFLKKRQQSMAAAAAAAAA
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Searching for TAT signals

• Pattern match (S/T)RRXFLK..Non-Hydrophobic

TRRSFLS..Non-Hydrophobic

• (PSSM (pattern match RRNon-Hydrophobic))

("TRRDAMA" "GRRRFLR" "SRRQFLT" "DRRRFLT"
"TRRDALR" "TRRGFLK" "TRRSFLK" "DRRTFMK" "SRRDFMK"
"NRRNFIK" "TRRDFLY" "GRRQFMN" "DRRTFLR" "SRRAFLS"
"TRREFIK" "SRRDLLK" "DRRKFLK" "SRRGLVK" "SRRDFVK"
"SRRSFLQ" "SRRGFLV" "SRRGFLV" "SRRGFLG" "SRRTFVK"
"SRRQFIQ" "SRRGFIG" "NRRDFIK" "SRRRFLA")

• Score (PSSM/Background)

0.51724136 / 0.058600802 8.826524

• S8102 MIT9313 PCC6803

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Observations
A sample of the results sorted by description

• (S8102.p-SynW0321 20.450802 "ABC transporter,
  membrane component")
• (S8102.p-SynW0924 19.10863 "ABC transporter,
  multidrug efflux family")
• (S8102.p-SynW1023 16.258312 "ABC transporter,
  multidrug efflux family")
• (S8102.p-SynW0825 17.05498 "ABC transporter,
  possibly multidrug efflux")

S8102- Total 1083 ABC transporter
53 Mit9313- Total 898 ABC transporter
46 PCC6803- Total 1221 ABC transporter 29
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ABC Transporter Proteins?

• Transport system
• 983 total 473 use TAT

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Possible Conclusions

• How do cyanobacteria protect secreted proteins?
• TAT pathway
• What kind of proteins use the TAT patway?
• ABC transporters

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Thanks to

• Brian Palenik