with open("ecoli.fasta", "r") as file:
    data = []
    file.readline()
    for line in file:
        data.append(line.strip())
    seq = "".join(data)


with open("oriC.fasta", "w") as file:
    print(">oriC of E. coli K12 MG1655", file=file)
    print(f"{seq[3_923_766:3_923_998]}", file=file)