Protection of Secreted Proteins in Cyanobacteria

Aaron Holman

How do cells secrete proteins?

• Most use Sec pathway

• Some use TAT pathway

• Signal sequence

Why?

• Harsh conditions inhibit folding

• Archae, Bacteria (Cyanobacteria)

Goals

• How do cyanobacteria protect secreted proteins?

• What kind of proteins use the TAT patway?

What is the TAT signal?

• (S/T)RRxFLK………[Non-hydrophobic]

QRSKKSRRTFLKKRQQSMAAAAAAAAA

Searching for TAT signals

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

• (PSSM (pattern match RR…[Non-Hydrophobic]))

• Score = (PSSM/Background)

• S8102 MIT9313 PCC6803

TRRSFLS..[Non-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") 0.51724136 / 0.058600802 = 8.826524

Observations

(#$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")

A sample of the results sorted by description

S8102- Total 1083 ABC transporter 53

Mit9313- Total 898 ABC transporter 46

PCC6803- Total 1221 ABC transporter 29

ABC Transporter Proteins?

• Transport system

• 983 total 473 use TAT

Possible Conclusions

• How do cyanobacteria protect secreted proteins?

• TAT pathway

• What kind of proteins use the TAT patway?

• ABC transporters

Thanks to

Brian Palenik